Preheat oven to 425° F. Place salmon (skin-side down) on a foil-lined baking pan. Coat with 1 tbsp. lemon juice and top with pepper and chili flakes. Bake for 15-20 minutes.
After salmon is thoroughly cooked, take out and let cool. In a separate bowl, mash avocados and add tomatoes. Once salmon has cooled, shred and add to mixture. Add seasonings and lemon juice to taste.