Preheat the oven broiler. Place eggplant in a roasting pan, and broil 5 minutes, turning occasionally, until about 1/2 the skin is scorched.
Place eggplant in microwave safe dish. Cook 5 minutes on high in the microwave, or until tender. Cool enough to handle, and remove skin, leaving some scorched bits. Cut into thick slices.
Heat oil in a skillet over medium heat, stir in the onion, and cook until tender. Mix in eggplant, and tomatoes. Season with cayenne pepper, salt, and black pepper. Continue to cook and stir until soft.