For the dressing: Combine the mayonnaise and sour cream in a small bowl. Finely chop the garlic in a food processor. Add herbs, onions, anchovy paste, and vinegar, blending until smooth. Transfer the ground herb mixture to the bowl, stirring until well-combined. Sauce can be made one day in advance. For the salad: Preheat oven to 350ºF. Place salmon on a greased baking sheet, skin side down. Drizzle the fish with olive oil and sprinkle with salt and pepper to taste. Bake for about 13 minutes for medium-well, or until desired temperature. Remove from oven and let cool. Meanwhile, bring water and 1/2 teaspoon salt to a boil. Add green beans and cook until tender, about four minutes. Drain and rinse with cold water. Remove skin from salmon. Loosely break up salmon fillet in a medium bowl. Stir in green beans, cucumber, red onion, and egg. Fold in dressing and chill until serving.