Preheat oven to 400ºF, prepare two aluminum foil bowls for the salmon to rest in, and place on the baking sheet.
Rinse salmon fillets in cold water, and pat dry with paper towels. Fold aluminum foil into two bowl shapes. Lay a salmon fillet in each foil bowl and leave unsealed.
Pour milk over each fillet (pro tip: cooking fish in milk is a technique that helps create a tender and flaky fish and rids the fillet of unwanted “fishiness”). Drizzle half of the hoisin over each fillet. Season each fillet with garlic, salt, ginger, and chili flakes.
Bake for 20 minutes, then broil on high for 5 minutes. The salmon should no longer be shiny, but rather an opaque pink shade that is firm and easily flakes with a fork.