Line a baking sheet with parchment paper; place salmon fillet on top.
Bake salmon in the preheated oven until easily flaked with a fork, about 15 minutes. Let cool, about 10 minutes. Flake into bite-sized pieces with a fork.
Combine cooled salmon, avocados, grape tomatoes, red bell pepper, and green onions in a large bowl. Drizzle lime juice and olive oil on top. Add kosher salt, black pepper, and chili powder; toss gently distribute evenly.
Chill salad until flavors combine, 2 hours to overnight.