Extra-virgin olive oil
1 tbsp. fresh lime juice
1 tsp. ground cumin
1 ripe hass avocado, peeled, seeded, and coarsely
3⁄4 cup fish stock
3 cloves garlic, finely chopped
1 3" piece ginger, peeled and finely chopped
1 medium tomato, cored, peeled, seeded, and finely
4 tbsp. cold butter, cut into small pieces
2 tbsp. cilantro leaves
Freshly ground black pepper
1. Heat oven to 500°. Place each piece of salmon between lightly oiled pieces of plastic wrap. Use smooth side of a meat mallet to gently pound each into a roughly 8" × 4" oval; transfer wrapped salmon filets to a plate. Combine lime juice, cumin, avocado, and salt to taste in a bowl and set aside.
2. Place 4 large heatproof plates in oven. Put fish stock, garlic, and ginger into a large skillet; bring to a boil. Reduce heat to medium and boil gently until thickened, 4–5 minutes. Add tomatoes; cook for 1 minute more. Remove from heat and whisk in 3 tbsp. butter a few pieces at a time; keep sauce hot. (Melt the remaining butter.) Carefully remove plates from oven. Brush plates with melted butter and top each with one piece of unwrapped salmon; season with salt and pepper to taste. Pour some of the sauce over each piece of salmon; garnish with the avocado relish and cilantro, then drizzle with a little olive oil. Serve immediately.