Preheat the oven to 400 degrees F (200 degrees C). Line a medium baking dish with aluminum foil; lightly grease foil.
Grind garlic, chile pepper, and olive oil together with a mortar and pestle. Add lime juice, mustard, salt, and black pepper; mix until a thick paste forms.
Place salmon fillets in the prepared baking dish; coat with mustard paste.
Bake in the preheated oven until salmon easily flakes with a fork, 12 to 15 minutes.
