Preheat oven to 180°C (356°F) with top and bottom heat.
Finely dice the onion and garlic. Heat 2 tablespoons oil in a large pan over medium heat. Add onion and garlic, cook for 3-4 minutes until translucent. Add minced meat, break it up with a spoon, and while cooking, add ajvar and harissa. Cook for another 4-5 minutes until meat is cooked through. Season with salt, pepper, and thyme. Add kidney beans and heat through for 2-3 minutes. Remove from heat.
Spread 2-3 heaping tablespoons of the chili mixture on the inside of each roll bottom. Top with grated cheese. Place on a baking rack and bake for 10 minutes until cheese begins to brown. Place the roll tops on each burger (do not press down). Bake for another 5 minutes.
Remove from oven. Lift off the roll tops. Add 1 teaspoon sour cream to each burger bottom. Replace the roll tops.