1. Pulse the white bread in the Omniblend until you have fine breadcrumbs. Keep it aside.
2. For the tahini mayonnaise, blend all the ingredients on high until smooth. Keep aside.
3. Blend the garlic and chilli until finely chopped. Add in the meat, salt, egg, bread crumbs and spices until smooth.
4. Shape into four burgers and chill in the fridge for 15 minutes, or until you are ready to cook them. Take them out of the fridge 30 minutes before you start cooking.
5. Preheat the grill to high. Place the burgers on a well-oiled baking sheet and cook for about 4-5 minutes on each side.
6. Meanwhile, to serve, split the buns in two. Spread the mayo on one half of the bun. Place a burger onto one half of each bun on a bed of lettuce and grilled eggplant. Place the feta cheese on top of the patty followed by red pepper. Finish with the other half of each bun.