Dice 1 of the onions. Heat a large pot over medium-high heat and add 4 tablespoons of the olive oil. Add the onion and sauté until lightly browned, about 5 minutes. Drain and rinse the chickpeas, kidney beans, and fava beans, and add them to the onion along with 4 of the minced cloves of garlic, the turmeric, and lentils. Sauté for 1 minute, then add the stock and bring to a boil. Boil the beans, covered, for 1 hour. Tilt the lid so the pot is partially covered and simmer, stirring occasionally, for 1 1/2 hours. Season with salt.

Slice the remaining 2 onions into thin half moons. Heat a sauté pan over high heat and add the remaining 3 tablespoons olive oil. Add the onions and fry, stirring frequently, until the onions are brown and caramelized. Add the remaining garlic and the mint and sauté for 1 minute. Season with salt and set aside.

Add the noodles to the soup and cook until tender, 6 to 8 minutes. When the noodles are almost done, add the leafy greens and the fresh herbs and cook for 2 minutes.

Serve with a large dollop of yogurt and a few tablespoons of the sautéed onion mixture.