Preheat your grill to medium-high heat.
In a bowl, toss the cherry tomatoes with 1 tablespoon of olive oil, salt, pepper, and garlic powder.
Spread the tomatoes on a baking sheet and roast in the oven at 400°F for about 15-20 minutes, or until they are blistered and soft.
While the tomatoes are roasting, brush the cod fillets with the remaining tablespoon of olive oil and season with salt and pepper.
Place the fillets on the grill and cook for about 4-5 minutes on each side, or until the fish flakes easily with a fork.
In a small bowl, combine the sour cream, dill, lemon juice, and Dijon mustard. Mix well until smooth.
Once the cod is cooked, serve it topped with the roasted tomatoes and a generous drizzle of the creamy dill sauce.