Preheat the oven to 400°F (200°C).

Rinse the fish under cold water and pat dry with paper towels. Place the fish on a large baking sheet lined with parchment paper.

Drizzle 2 tablespoons of olive oil over the fish, rubbing it into the skin. Season the inside and outside of the fish with salt, pepper, oregano, and thyme.

Stuff the cavity of each fish with lemon slices, half of the cherry tomatoes, and half of the red onion.

Scatter the remaining cherry tomatoes and red onion around the fish on the baking sheet. Add minced garlic on top of the vegetables.

Drizzle the remaining tablespoon of olive oil over the vegetables and season with salt and pepper.

Bake in the preheated oven for 25-30 minutes, or until the fish flakes easily with a fork and the vegetables are tender.

Remove from the oven and let it rest for a few minutes. Garnish with chopped parsley before serving.