01 - Heat oven to 400°F. Line a baking sheet with parchment paper for easy cleanup.
02 - Combine halved cherry tomatoes, olive oil, minced garlic, salt, black pepper, and thyme leaves in a bowl. Toss to coat. Spread tomatoes evenly on the prepared baking sheet and roast for 15 to 18 minutes until soft and caramelized.
03 - In a small bowl, whisk olive oil, lemon zest, lemon juice, salt, and pepper together. Lightly brush mixture over both sides of the cod fillets.
04 - Heat a grill or grill pan over medium-high heat and lightly oil the grates.
05 - Place marinated cod fillets on the hot grill. Cook for 3 to 4 minutes per side until the fish turns opaque and flakes easily with a fork. Remove from grill and let rest briefly.
06 - In a small bowl, combine sour cream, mayonnaise, dill, lemon juice, Dijon mustard, salt, and black pepper. Stir until smooth. Adjust seasoning if necessary.
07 - Arrange grilled cod on serving plates. Top with roasted tomatoes and drizzle generously with creamy dill sauce. Garnish with additional dill if desired.