In a medium pot, combine rinsed quinoa and vegetable broth. Bring to a boil, then reduce heat and cover. Simmer for 15 minutes until quinoa absorbs all the water and is fluffy. Set aside.
In a large skillet, heat olive oil over medium heat. Add diced onion and bell pepper, sauté for about 5 minutes until softened.
Stir in corn, black beans, cumin, paprika, cayenne pepper (if using), lime juice, salt, and pepper. Cook for an additional 5-7 minutes to allow flavors to meld.
To assemble bowls, place a base of quinoa in each bowl, then layer with the black bean and corn mixture. Top with diced avocado and halved cherry tomatoes.
Garnish with fresh cilantro and add an extra squeeze of lime if desired.