To make the dressing, blend the tahini, garlic, cumin, cayenne, and lemon juice in a food processor until creamy. Slowly poor the oil, then gradually add water to make a creamy dressing.
Bring a pan of water to a boil. Add the salt and sprinkle in the rice; simmer for 15-20 minutes, or until the rice is just tender. Drain and rinse, then set aside.
Heat the olive oil in a large pan. Add the onion and garlic, and cook until they begin to soften. Stir in the curry powder and chili, and cook for 2 minutes. Add the pepper, peas, leek, and chopped tomato flesh, and cook gently for 7 minutes, or until tender. Set aside.
Process the garbanzo beans in the food processor until smooth. Add half the vegetables and process again. Transfer to a large bowl and add the remaining vegetable mixture, bread crumbs, chopped fresh cilantro, and egg; mix well. Stir in the rice and season well. Chill for 1 hour, then shape into 4-6 patties.
Cook the patties in oil for 6-8 minutes, or until golden, and serve with the dressing, garnished with slices of cucumber and wedges of lime.