In a large pot, pour in the vegetable broth and place it over medium heat. Bring the broth to a gentle simmer while stirring occasionally, for about 5 minutes.

Add the black beans, corn, and chopped vegetables. Sprinkle in the chili powder, cumin, smoked paprika, and a pinch of salt. Stir to combine, and let it simmer for 10-15 minutes.

In a mixing bowl, combine the masa harina, baking powder, and salt. Gradually stir in water until it forms a dough-like texture.

Drop spoonfuls of the dumpling mixture into the simmering soup. Cover and let the dumplings cook for 10-12 minutes without lifting the lid.

Remove the pot from heat. Stir in lime juice and adjust seasoning if necessary. Serve in bowls with optional toppings.