Place salmon skin-side down on a sheet pan. Season with garlic powder and black pepper. Bake for 15 minutes.
While the salmon is baking, cook the vegetables in a pan over medium heat: Add some oil, then onions, garlic, and bell pepper. Cook for 5 minutes, or until tender.
Flake the salmon in a bowl. Add the vegetables and all the other ingredients. Form into balls, then flatten into patties.
Add one patty at a time to the pan. Cook for 2-3 minutes each side, or until the patty starts to brown.
Make tartar sauce by mixing together all ingredients.