Cut the onions into fine rings. Chop herbs. Finely dice the garlic. Cut the tomatoes and feta into slices.
Preheat the oven to 200 degrees (convection 180 degrees). Sauté the onion rings in a pan with 1 tablespoon of olive oil. Mix the herbs, lemon juice, remaining olive oil, pesto and garlic together. Layer the onions, feta, tomatoes and olives alternately in a baking dish. Brush the layers with the mixed pesto sauce.
Bake in the oven on the middle rack for about 15 - 20 minutes.
Notes
You can vary the herbs. You can also use mozzarella or goat cheese instead of feta.