Preheat oven to 400˚F. Place the rack in the center of the oven. Line a medium-size roasting pan with foil (unless you don’t mind washing the pan, then you don’t need to line it) and then line it with parchment, leaving an overhang.
Make 4-5 diagonal shallow slits in the skin and flesh of the fish, season the fish inside and out with less than half of the pepper. Place the fish inside the parchment lined roasting pan,
1 arctic char
Slice half the onion into half moon slices and finely dice the other half. Distribute the sliced onion around the fish.
1 large red onion
In a small mixing bowl, mix together the diced onion, diced tomato, juice from half of the lemon, the chopped basil (if using) and pepper. Drizzle with some of the olive oil, mix this all up. Stuff this mixture inside the cavity of the fish.
1 large tomato, 1 lemon, 10 leaves basil
Place the cherry tomatoes all around the fish. Drizzle the whole thing with a little more of the olive oil (save a little bit), season with pepper, squeeze the other half of the lemon over the fish and tomatoes and place the two lemon halves in the roasting pan.
15 cherry tomato, 3 tbsp olive oil, 1 pinch pepper
Bake for 20 minutes, and remove from the oven. Place half of the asparagus on either side of the fish, nestle them in a little and drizzle with the rest of the olive oil, put the pan back into the oven and continue roasting for another 20-25 minutes. You know it is ready when the skin of the fish blisters a little and turns golden brown and the skin splits a little.
1 bunch asparagus
Cut the flesh of the fish in sections and serve without the skin.