Preparation Place salmon in heavy medium skillet. Season with salt and pepper. Sprinkle with tarragon. Add enough water to skillet to just cover salmon. Cover and simmer salmon over medium-low heat until salmon is opaque but still pink in center, about 7 minutes. Using spatula, transfer salmon to plate and refrigerate until chilled. Reserve water in skillet. Return water in skillet to boil. Add potatoes to skillet. Cover and simmer until potatoes are just tender when pierced with knife, about 10 minutes. Transfer potatoes to plate. Cool and slice. Reserve water in skillet. Add enough additional water to skillet to cover bottom by 1 inch. Bring water to boil. Add beans. Cover and simmer over high heat until beans are crisp-tender, about 4 minutes. Rinse beans under cold water to cool. Drain. (Can be prepared up to 6 hours ahead; refrigerate.) Arrange lettuce leaves on each of 2 plates. Top each with salmon fillet. Arrange half of potatoes, green beans, tomatoes and hard-boiled eggs decoratively around each salmon fillet. Sprinkle half of green onions and capers over each salmon fillet. Serve, passing vinaigrette separately.
Preparation Place salmon in heavy medium skillet. Season with salt and pepper. Sprinkle with tarragon. Add enough water to skillet to just cover salmon. Cover and simmer salmon over medium-low heat until salmon is opaque but still pink in center, about 7 minutes. Using spatula, transfer salmon to plate and refrigerate until chilled. Reserve water in skillet. Return water in skillet to boil. Add potatoes to skillet. Cover and simmer until potatoes are just tender when pierced with knife, about 10 minutes. Transfer potatoes to plate. Cool and slice. Reserve water in skillet. Add enough additional water to skillet to cover bottom by 1 inch. Bring water to boil. Add beans. Cover and simmer over high heat until beans are crisp-tender, about 4 minutes. Rinse beans under cold water to cool. Drain. (Can be prepared up to 6 hours ahead; refrigerate.) Arrange lettuce leaves on each of 2 plates. Top each with salmon fillet. Arrange half of potatoes, green beans, tomatoes and hard-boiled eggs decoratively around each salmon fillet. Sprinkle half of green onions and capers over each salmon fillet. Serve, passing vinaigrette separately.