1. Sprinkle lemon juice and half of the lemon thyme inside sardines.
2. Brush both sides of sardines using 2 tbs of the olive oil; season with salt and pepper.
3. Heat grill pan and cook sardines for 3 to 4 minutes on each side or until skin on the fish is crisp and golden.
4. Combine tomatoes in a medium bowl with garlic and remaining lemon thyme and olive oil.
5. Serve sardines on toasted rye with diced tomatoes and any juice from the tomatoes.