Heat a medium pot with extra-virgin olive oil over medium heat. Add garlic and cook 2 to 3 minutes. Grind the chickpeas and onion in food processor. Add to pot and cook 5 minutes to sweeten onion. Season the chickpeas with cumin, cardamom, turmeric, salt and pepper. Stir in stock, then tomatoes. Simmer soup 5 to 10 minutes to combine flavors. Serve with a dollop of yogurt and warm pita for dipping.