Makes 4 servings
For the mustard-herb butter
- 5 Tbs unsalted butter, softened
- 1 Tbs chopped chives
- 1 tsp chopped tarragon
- 2 tsp grainy mustard
- 2 tsp fresh lemon juice
- 1/4 tsp salt
- 1/4 tsp pepper
- 1 cup French green lentils
- 4 cups water
- 2 medium leeks (white and pale green parts only)
- 1 Tbs unsalted butter
- 1/2 to 1 Tbs fresh lemon juice
- 3/4 tsp salt
- 4 (6-ounce) fillets of skinless wild-caught salmon
- 2 Tbs unsalted butter
- 1/2 tsp salt and 1/4 tsp pepper mixed together
Make the mustard-herb butter:
Stir together all ingredients with 1/4 tsp each of salt and pepper.
Cook the lentils:
Bring lentils, water, and 3/4 tsp salt to a boil in a heavy medium saucepan, then reduce heat and simmer, uncovered, until lentils are just tender, 20 to 25 minutes. Remove from heat and let stand 5 minutes. Reserve 1/2 cup cooking liquid, then drain lentils.
While lentils cook, chop leeks, then wash thoroughly. Cook leeks in butter in a heavy medium skillet over medium-low heat, stirring occasionally, until softened, 6 to 8 minutes.
Add lentils with reserved cooking liquid to leeks along with 3 Tbs mustard-herb butter and cook, stirring, until lentils are heated through and butter is melted. Add lemon juice and salt and pepper to taste. Remove from heat and keep warm, covered.
Sauté salmon while leeks cook:
Pat salmon dry and sprinkle with salt and pepper mixture; distribute evenly between fillets.
Heat butter in a large nonstick skillet over medium-high heat until foam subsides, then sauté salmon, turning once, until golden and just cooked through, 6 to 8 minutes total.
Serve salmon, topped with remaining mustard-herb butter, over lentils.
Cook's notes: Mustard-herb butter can be made 1 day ahead and chilled, covered. Soften at room temperature before using (1 hour)
Lentils can be cooked (but not drained) 1 day ahead and chilled in cooking liquid, covered (once cool).