# Seared Sous Vide Ahi Tuna with Corn Purée, Koji Dragon Tongue Beans, and Roasted Sweet Potatoes > Thick slices of seared ahi sit over silky sweet-corn purée, with tender dragon tongue beans carrying the savory depth of mushroom garum and barley koji. Roasted sweet potatoes bring caramelized edges and soft orange flesh—a late-summer plate built around sweet vegetables and clean, gently cooked fish. - URL: https://www.chezjk.com/recipes/seared-sous-vide-ahi-over-corn-puree-with-dragon-tongue-beans-mushroom-garum-bar - Author: Jonathan Katzman - Cooked and photographed: 2024-09-04 - Recipe updated: 2026-10-23 - Serves: 4 servings - Tags: pescatarian, nut-free ![Seared Sous Vide Ahi Tuna with Corn Purée, Koji Dragon Tongue Beans, and Roasted Sweet Potatoes](https://www.chezjk.com/api/images?path=9e5d6860-dd86-455e-b57b-e352c363fc57%2F748b11481961f788.jpg) ## Seared Sous Vide Ahi Tuna A controlled water bath gives the tuna an evenly pink interior. Thorough drying and a very brief sear build a browned exterior without cooking a thick gray band around the fish. ### Ingredients - 1½ lb ahi tuna steaks, approximately 1 inch thick, suitable for serving undercooked - ¾ tsp fine sea salt - ¼ tsp freshly ground black pepper - 1 tbsp ghee ### Instructions 1. Heat a sous vide bath to 54°C / 129°F. Season the tuna with salt and pepper, then seal in a single layer in a suitable cooking bag using gentle vacuum pressure or water displacement. 2. Cook 1-inch-thick steaks for 45–60 minutes. This produces a warm pink center rather than a raw-red center. 3. Remove the tuna from the bag and blot extremely dry. Let it stand on a rack for 3–5 minutes while a heavy skillet heats over high heat. 4. Add the ghee to the hot skillet. Sear the tuna for 20–30 seconds on each broad face, then briefly touch the edges to the pan. Work in batches if needed so the pan stays hot. 5. Slice across the grain into ½-inch-thick pieces and serve immediately. ### Notes - This low-temperature treatment does not pasteurize the tuna. Use properly handled fish from a trusted supplier; people at higher risk of foodborne illness should have fish cooked to 145°F / 63°C instead. - The timing assumes steaks about 1 inch thick; substantially thicker pieces require a thickness-specific sous vide schedule. ## Silky Corn Purée Fresh corn supplies both sweetness and enough starch to make a smooth sauce without cream. A little butter rounds it out, while lemon keeps the finish lively beside the tuna. ### Ingredients - 4 large ears sweet corn, husked - 2 tbsp unsalted butter, divided - ½ cup water, plus more as needed - ½ tsp fine sea salt, plus more to taste - 1 tsp fresh lemon juice ### Instructions 1. Cut the kernels from the cobs. Scrape the cobs with the back of a knife to collect their milky juices. 2. Put the kernels, corn juices, water, salt, and 1 tablespoon butter in a saucepan. Cover and simmer gently for 8–12 minutes, stirring occasionally, until the kernels are tender. Do not brown. 3. Transfer to a blender and add the remaining butter. Blend until very smooth, venting the lid safely for hot ingredients. Add hot water a tablespoon at a time if needed to keep the blades moving. 4. Pass through a fine-mesh sieve, pressing firmly and discarding the coarse skins. Stir in the lemon juice and adjust the salt. 5. Keep warm over very low heat. The purée should spread slowly beneath the fish rather than run across the plate. ### Notes - If the purée is too loose, reduce it gently while stirring. If too thick, loosen with hot water just before plating. ## Dragon Tongue Beans with Mushroom Garum and Barley Koji Gentle covered cooking softens the broad pods while preserving their shape. Mushroom garum and barley koji give the cooking juices deep savory flavor without overwhelming the beans. ### Ingredients - 1 lb dragon tongue beans, stem ends trimmed - 1 tbsp olive oil - ½ cup water, plus more as needed - 2 tbsp food-grade barley koji grains, crumbled - 2 tsp mushroom garum, plus more to taste - 1 tsp unseasoned rice vinegar ### Instructions 1. Combine the beans, olive oil, water, barley koji, and mushroom garum in a wide sauté pan. Bring to a gentle simmer and cover. 2. Cook for 10–15 minutes, turning the beans occasionally, until the pods are tender but still intact and the koji grains have softened. Add a splash of water if the pan begins to dry. 3. Uncover and simmer for 2–3 minutes to reduce the liquid to a light coating. The beans' purple streaks will largely disappear during cooking. 4. Add the rice vinegar. Taste a bean with some cooking juices and add more mushroom garum only if it needs salt. ### Notes - Use prepared food-grade koji, not koji starter spores. If using dried barley koji, soak it in the measured water for 20 minutes before cooking; extend the simmer if the grains remain firm. - Garum varies substantially in saltiness, so begin with the measured amount and adjust at the end. ## Roasted Sweet Potatoes Roasting the potatoes whole concentrates their sweetness and gives the skins browned, chewy edges. Breaking them open rather than neatly slicing them exposes the soft flesh for a simple butter finish. ### Ingredients - 1½ lb orange-fleshed sweet potatoes, preferably 3–4 similarly sized potatoes - 2 tsp olive oil - ½ tsp fine sea salt - 1 tbsp unsalted butter ### Instructions 1. Heat the oven to 425°F / 220°C. Scrub and dry the sweet potatoes, prick each a few times, and rub with olive oil and salt. 2. Place on a parchment-lined rimmed baking sheet and roast for 55–70 minutes, turning once, until the skins are browned and a knife slides through the thickest part without resistance. 3. Rest for 5 minutes, then split and break into large irregular pieces. Distribute the butter over the hot flesh and season to taste. ### Notes - Keep the skins attached where possible for contrast with the soft centers. Larger potatoes may need additional roasting time. ## Overall Timing / Workflow Start the long-cooking potatoes first, then overlap the tuna bath with the vegetables. Save the tuna sear for the last moment so all components reach the plate warm. ### Instructions 1. 0:00 — Heat the oven and sous vide bath. Prepare the sweet potatoes and put them in the oven. 2. 0:10 — Season and bag the tuna. Put it in the water bath once it reaches 54°C / 129°F. 3. 0:20 — Cut the corn and trim the beans. Soak dried barley koji now if using it. 4. 0:35 — Cook, blend, and strain the corn purée; hold it warm over very low heat. 5. 0:45 — Start the beans. Check the sweet potatoes and continue roasting until completely tender. 6. 1:00 — Finish the beans and break open the roasted sweet potatoes. Remove the tuna after its 45–60-minute bath, dry it thoroughly, and heat the skillet. 7. 1:10–1:20 — Sear and slice the tuna, adjust the purée consistency, and plate immediately. Allow extra time if the potatoes need it. ## Plating A broad pool of corn purée anchors the tuna, while keeping the beans and sweet potatoes distinct preserves their contrasting textures. ### Instructions 1. Spoon a broad swoosh of warm corn purée onto each warmed plate. 2. Arrange the tuna slices in an overlapping fan partly over the purée, leaving their pink interiors visible. 3. Place the whole beans alongside the fish with just enough cooking juices to gloss them. 4. Add a loose cluster of broken roasted sweet potatoes, keeping their browned skins and orange flesh visible. ## Leftover Path Separate storage keeps the corn purée smooth and prevents the vegetables from soaking the fish. The tuna is best cooked only in the quantity needed because reheating quickly changes its texture. ### Instructions 1. Refrigerate leftovers promptly in separate shallow, covered containers, within 2 hours of cooking. 2. Because the tuna was served undercooked and was not pasteurized, plan to eat it immediately rather than save it. If retained, refrigerate promptly and use within 24 hours, reheating to 145°F / 63°C; it will become firm and opaque. 3. Use the corn purée, beans, and sweet potatoes within 3 days. Rewarm the purée gently with a splash of water, steam the beans with a spoonful of water, and reheat the sweet potatoes in a 375°F / 190°C oven until hot. 4. For another meal, spoon the reheated beans and sweet potatoes over the warmed corn purée. --- From ChezJK (https://www.chezjk.com), Jonathan Katzman's public home-cooking archive: every meal he has photographed, written up as a recipe you can cook.