Peel the onions and finely dice. Mix with the ground beef, eggs and breadcrumbs and season with salt and pepper. Cut the peppers into quarters, remove the stems, seeds and pith, rinse and cut into small cubes. Heat the olive oil in a large frying pan and sauté the peppers briefly.
Peel the garlic and slice. Crumble the feta. Finely slice the tomatoes. Mix the peppers, cheese, tomatoes and chopped herbs into the meat mixture and mix until smooth.
Line a terrine mold (or loaf pan) with parchment paper, fill with the meatloaf mixture, smooth the surface and top with the herb sprigs. Put the lid on (or cover with foil) and bake in a preheated oven at 200°C (approximately 400°F) for 45-50 minutes.
Drain the excess fat from the surface and invert onto a piece of parchment paper. Slice to serve.