To make Tom Kerridge's mexican style rice recipe, you'll first need to prepare the rice. In a large skillet, heat the oil over medium-high heat. Add the onion and cook, stirring frequently, until the onions are translucent, about 5 minutes. Stir in the garlic, cumin, salt, and pepper. Cook and stir for 1 minute. Remove the skillet from the heat and add the water. Bring the mixture to boil, then cover and simmer for 20 minutes, or until tender. Serve with sour cream and guacamole.