Rinse the rice well under cold water for 1 minute. Add the oil to a pot and bring the heat to medium. Drop in the garlic and onion and cook for 3 minutes. Add the rice and toast for 3 minutes.
Add 2 cups of water and bring to a boil, cover, then simmer over heat to low for 15 minutes, until the rice is tender. Remove the pot from the heat.
Add ½ of the cucumber and one avocado to a blender along with ¼ cup of water, salt, and pepper. Blend until smooth then dice up the remaining cucumber and avocado. Pour the blended sauce into the pot of rice and stir.
Put the rice into a serving bowl, top with the remaining diced cucumber, and diced avocado. Add the chopped cilantro and serve.