Heat oven to 375°F.
Spread the rice into an 8-inch square glass baking dish. Stir in a tablespoon of the oil and a teaspoon of the salt.
Bring the water to a boil in an electric kettle and pour over the rice. Cover tightly with heavy-duty aluminum foil and bake on the middle rack of the oven for 1 hour.
Meanwhile, place a 12-inch saute pan over medium heat. When the pan is hot, add the remaining 3 tablespoons of olive oil to cover the bottom of the pan and add the garlic and red pepper flake. Cook, stirring frequently, until the garlic is golden brown, 3 to 5 minutes.
Add the onion and remaining salt, and cook, stirring often, until the onion starts to color, 1 to 2 minutes. Then, add the black beans, oregano, and black pepper. Cook, stirring frequently, for 6 to 8 minutes.
Remove the cover from the rice, fluff with a fork, and allow to "steam out" for 2 minutes. Serve the beans over the rice, and garnish with avocado and cilantro.