Preheat your grill to medium-high heat.
In a mixing bowl, toss the halved cherry tomatoes with 1 tablespoon of olive oil, salt, black 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, prepare the creamy dill sauce by combining sour cream, dill, lemon juice, and Dijon mustard in a small bowl. Mix well and set aside.
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 per side, or until the fish flakes easily with a fork.
Once the cod is cooked and the tomatoes are roasted, serve the cod topped with the roasted tomatoes and a generous drizzle of the creamy dill sauce.