In a heavy 6-quart pot, heat the oil over medium-high heat. Add the meat and stir with a large wooden spoon to break up the meat. Cook, stirring, until the meat is brown and cooked through, 5 minutes. Add the onions, garlic, chili powder, essence, salt, cumin, and black pepper, and cook, stirring, until soft, 4 minutes. Add the tomatoes, tomato paste, sugar, and water. Stir well and bring to a boil. Lower the heat to medium-low and simmer uncovered for 30 minutes. Keep warm until ready to serve.