Heat oil in a saucepan over medium heat; cook and stir onion and garlic until lightly browned, about 10 minutes.
Mix quinoa into onion mixture and cover with vegetable broth; season with cumin, cayenne pepper, salt, and pepper. Bring the mixture to a boil. Cover, reduce heat, and simmer until quinoa is tender and broth is absorbed, about 20 minutes.
Stir frozen corn into the saucepan, and continue to simmer until heated through, about 5 minutes; mix in the black beans and cilantro.