Lobster Shell Stock

Spread cracked lobster shells and heads on a large, rimmed baking sheet. Drizzle with olive oil and toss to coat. Roast at 220 C (425 F) for 15–20 minutes, turning once, until the shells are deeply caramelized — red-orange turning to mahogany — and the oven smells of roasted seafood. This Maillard reaction on the shells is the source of the stock's depth.

Transfer roasted shells to a large stockpot. Add butter and sauté the shallots, carrot, celery, and garlic directly in the pot with the shells over medium-high heat for 5–7 minutes until the vegetables are softened and golden. Deglaze the roasting tray with a splash of wine and scrape all the caramelized bits into the pot.

Add tomato paste to the pot and stir over medium-high heat for 2–3 minutes until the paste darkens and caramelizes. Remove the pot from the heat briefly and pour in the cognac — step back, the alcohol will ignite if using a gas flame. Let the flame die down or alcohol cook off for 30 seconds. Return to heat, add white wine, and bring to a boil. Reduce the wine by half.

Add crushed tomatoes, cold water or fish stock, tarragon, bay leaves, peppercorns, chili, and salt. Bring to a gentle boil, then reduce to a slow simmer. Skim any foam from the surface in the first 15 minutes. Simmer uncovered for 45–60 minutes, until the stock has reduced by approximately one-third and is deeply flavored and a rich orange-red color.

Remove from heat. Pour the stock through a fine-mesh strainer placed over a large bowl. Press the shells firmly with the back of a ladle to extract every last drop of flavor. Strain a second time through a cheesecloth-lined strainer for maximum clarity if using for a refined bisque. Taste and adjust seasoning. Cool rapidly over an ice bath and refrigerate for up to 3 days, or freeze in small portions.