Preheat oven to 200 C/180 Fan & oil a baking dish large enough to hold the 4 fillets.
Place the onions, garlic, capsicum & the rosemary in the dish, drizzle over 2 tbsp of the olive oil, add the juice & sprinkle over some salt and freshly ground black pepper, mix well and roast for 15 minutes.
At the end of that time, place the salmon fillets on the vegetables.
Add the cherry tomatoes, sandwiching them nicely amongst the salmon.
Drizzle the rest of the olive oil on, along with the salt and pepper. Use a brush to brush and distribute the olive oil on to the salmon and vegetables, if need be.
Roast, uncovered for 20-25 minutes until the salmons are lightly browned.
Serve with sautéed baby potatoes, mango and avocado salsa, a green salad and some mayonnaise & a squeeze of lemon juice.