Preheat oven to 400f
Lay fennel rounds on large baking sheet and drizzle with oil. Blend well to coat fennel.
Place salmon skin side down on top of fennel, sprinkle with salt and then spread mustard on top. Sprinkle crushed fennel and coriander. Press down gently.
Roast until fork comes out clean. Option to sprinkle fennel fronds on top.