Cook the rice according to package instructions. Combine the cooked and cooled rice with drained beans, corn, tomato, avocado, and spices. Toss together with olive oil and the juice of 1 lime. Set aside.
Once salad is assembled, add all the ingredients for the chimichurri sauce into a food processor. Pulse until the the onion and garlic are chopped and the ingredients are combined.
Pour sauce on top of salad and serve immediately or store the sauce in a sealed container in the fridge for up to 3 days.