Fill a saucepan with enough water to cover onions and bring to a boil. Add onions and simmer covered for 3-5 minutes.Drain. When cool enough to handle cut off the roots and peel away the tough skins.
In a nonstick skillet over medium low heat melt butter and then add the onions, cook stirring often until golden brown (15 minutes). Stir in sugar and cook s tiring until onions are glazed (5 minutes). Add salt and pepper and keep warm.
In a spice grinder or mortar and pestle combine the spices (coriander -peppercorns) and grind spices until coarsely ground. Rub both sides of the salmon with the spice mixture.
Spray a nonstick skillet with Pam and set over high heat. Add salmon and cook turning once until fish is browned on the outside and opaque in the center (3-5 minutes per side).
Divide and arrange the lentils on each of 4 plates. Place salmon in the middle of the lentils and garnish with the glazed onions and frisee.