1. Add the rice and 1 Tbsp oil or butter into a medium pot along with 2 cups of water. Increase heat to medium-high and bring to a simmer. Immediately reduce the heat to low-medium, and cover with a lid. Cook the rice until tender and the water is absorbed. For white long-grain rice this will take 13-20 minutes. Follow the directions on your specific package for best results.
2. Meanwhile, in a large wok or skillet, add the oil and melt it over medium heat. Stir in the onion and garlic, along with a pinch of salt, and sauté for about 5-6 minutes, until softened.
3. Stir in the chopped tomatoes, chili powder, garlic powder, dried oregano, cayenne (if using), and 1/2 teaspoon of salt. Continue sautéing for another 3-5 minutes (increasing/reducing heat if necessary), until the tomato softens.
4. Stir in the tomato paste and the drained and rinsed black beans. Cook for a few more minutes until heated throughout. Taste and add more salt if desired. Stir in the cilantro. Leave the mixture over low heat until ready to serve or simply turn off the heat and reheat before serving.
5. Prepare the Avocado-Lime Sauce by first mincing the garlic clove in a mini food processor (or use a regular size processor, if necessary). Add the avocado flesh, lime juice, water, and salt. Process until smooth. Adjust lime juice if desired.
6. When the rice is ready, reheat the bean mixture, if necessary. Divide the rice between 2-3 bowls. Top each with a couple scoops of the hot black bean mixture, and a large spoonful of both the salsa and the Avocado-Lime Sauce. Garnish with sliced green onion and optional sliced grape tomatoes.
