Tonno Recipe

Prepare tuna

Pat the tuna loin dry with paper towels. Trim any sinew or connective tissue. Lightly brush both sides with 1 tbs olive oil. Season evenly with kosher salt, black pepper, and lemon zest.

Sear tuna

Heat a heavy skillet or cast-iron pan over high heat until shimmering. Add 1 tbs olive oil and swirl to coat. Place the tuna in the hot pan and sear 45–60 seconds per side for rare (adjust to 75–90 seconds per side for medium-rare). Do not move the fish while searing. Remove from pan and let rest 3–4 minutes before slicing thinly against the grain into 1/4-inch slices.

Sweat aromatics

In a medium saucepan or sauté pan over medium heat, add 2 tbs butter and 1 tbs olive oil. When butter melts, add the diced onion, carrot, celery, leeks, and a pinch of salt. Cook, stirring occasionally, until vegetables are softened and beginning to caramelize, about 10–12 minutes.

Add mushrooms and garlic

Add the finely chopped mushrooms and minced garlic to the pan. Continue to cook until mushrooms release their moisture and brown lightly, another 5–7 minutes.

Incorporate tomato paste

Push the vegetables to the side, add the tomato paste to the center of the pan and cook for 2–3 minutes, stirring frequently, until it deepens in color — this develops a rich, slightly sweet base flavor.

Deglaze

Pour in the dry white wine to deglaze the pan, scraping up any browned bits from the bottom. Let the wine reduce by about half, approximately 3–5 minutes.

Simmer with stock

Add the vegetable stock, soy sauce, balsamic vinegar, thyme sprigs, and bay leaf. Bring to a gentle simmer, then reduce heat to low and simmer, uncovered, until the liquid is reduced by about one-third and visibly thickened, 25–30 minutes.

Finish and strain

Remove from heat. Fish out and discard thyme sprigs and bay leaf. Using an immersion blender (or transfer to a blender), purée the mixture until smooth. Strain the purée through a fine-mesh sieve into a clean saucepan, pressing on solids to extract flavor. Return the strained sauce to low heat.

Mount the sauce

Whisk in the cold cubed butter a little at a time to give the sauce a silky sheen and to slightly thicken it. Taste and adjust seasoning with salt and pepper. If sauce is too thick, thin with up to 2 tbs warm stock; if too thin, simmer gently to reduce further.

Warm plates. Spoon a generous smear or pool of the vegetable demi-glace onto each plate.

Fan sliced seared tuna over the sauce (about 6–8 slices per portion for a 1 lb loin serving 4). Drizzle any resting juices from the tuna over the slices.

Scatter microgreens or baby arugula beside or atop the tuna, drizzle with 1 tsp extra-virgin olive oil and a light squeeze of lemon. Serve immediately with lemon wedges.