Heat olive oil in a saucepan over medium-high heat; saute onion, tomato, and garlic until softened, about 10 minutes. Stir fava beans, lemon juice, cumin, and turmeric into onion mixture; cook until heated through, 3 to 5 minutes. Stir tahini into fava bean mixture and cook until warmed, 2 to 3 minutes; season with salt and pepper.
Pour fava bean mixture into a blender no more than half full. Cover and hold lid down; pulse a few times before leaving on to blend. Puree in batches until smooth.