• First, make the mustard butter. Stir together all butter ingredients along with 1/4 tsp each of fresh cracked pepper and Kosher salt. Set aside but keep at room temperature

For Lentils

• Bring lentils, water and 3/4 tsp salt to a boil in a heavy medium saucepan. Reduce heat and simmer, uncovered, until lentils are just tender, about 20-25 minutes.
• Remove lentils from heat and let stand 5 minutes. Reserve 1/2 cup cooking liquid then drain lentils.
• While the lentils are cooking, cut leeks in 1/2 lengthwise and rinse to remove sand. Chop leeks. Cook leeks in butter in a medium skillet over medium-low heat, stirring occasionally until softened but not brown, about 6-8 minutes.
• Add the drained lentils to the leeks, along with reserved cooking liquid. Add 3 Tbsp of the reserved mustard butter, and cook, stirring, until lentils are cooked through and the butter is melted. Add lemon juice, salt and pepper to taste. Remove lentils from heat, but keep warm, covered until ready to plate.

For Salmon

• While the leeks are cooking, pat salmon filets dry and season lightly with a little salt and fresh pepper.
• Heat butter in a large non-stick skillet over medium-high heat until foam subsides. Place salmon, presentation side down and cook until just golden. Turn once during cooking process until salmon is just barely cooked through (or cooked to taste), 6-8 minutes total.
• To serve, place a small mound of lentils at the top middle of the plate. Place a piece of salmon on top of lentils along with a spoonful of the remaining mustard-herb butter. If desired, garnish with additional chives and fresh cracked pepper.