Heat Canola oil in a stock pot, add chopped onion and sauté for a few minutes till it softens and begins to brown.
Add the garlic and continue to sauté for 2 minutes longer
Pour into the pot, 1 quart vegetable broth, 2 cups water, stir in the tomato and pepper paste, salt, all spice, stir well
Add the fresh fava beans, reduce heat to a low simmer, cover the pot with a lid, and let it cook for 30 minutes
Add the frozen fava beans, and cook for another 30 minutes, or longer until the beans are soft.
Prepare the yogurt dressing by combining the yogurt, garlic and 2 tablespoons of the water in a small bowl, mix well, add the remaining 2 tablespoons of water, mix until smooth (If you add all the water in at once, the mixture will not blend and the yogurt will be lumpy.)
