To prepare the salad: Place the tomatoes, onion and avocados in a bowl. Mix together the oil, fresh coriander, lime juice and cumin. Pour this over the vegetables and season. Mix well and set aside while you prepare the beef.
To prepare the beef: In a large bowl, toss the steak with 1 tablespoon oil, the chipotle paste and lime juice. Mix well.
To cook the beef: Heat a little oil in a large frying pan or wok over high heat. Add half the beef and cook for 2-3 minutes until browned on all sides. Set aside and keep warm. Add a little more oil to the pan and cook the rest of the beef.
To serve: Divide the rice into 4 bowls, top with steak then the Avocado and Tomato salad and a spoonful of sour cream.