Position oven rack 4 inches from broiler; preheat broiler to high. Place chiles on rimmed baking pan; broil 7 minutes or until lightly charred, turning once. Transfer chiles to cutting board; coarsely chop.
On same baking pan, place bread slices and spray with cooking spray; broil 2 minutes or until golden brown, turning once.
In medium bowl, mash avocados; stir in lime juice, salt, pepper and chopped chiles. Spread avocado mixture over toast; top with salmon, cucumber, onion, dill, tarragon and pepper.