Heat oven to 400 F. Line rimmed baking sheet with parchment paper.

In bowl, toss red peppers, tomatoes, onion, and garlic with 2 tsp oil and salt. Spread out on prepared baking sheet and roast in preheated oven for 35 minutes, tossing once halfway through. Turn on oven broiler and heat until vegetables have some blackening, about 5 minutes.

In large saucepan, heat remaining 2 tsp oil. Remove sausage from casings and add to pan, breaking meat into pieces. Heat until sausage is cooked through. Add chili powder, oregano, and cumin to pan; heat 30 seconds. Place 6 cups water, quinoa, black beans, and cooked vegetables along with any juices into saucepan. Bring to a boil, reduce heat to medium-low, and simmer for 15 minutes, or until quinoa is tender. Add corn to pan and heat 1 minute.

Ladle soup into serving bowls and squeeze in lime juice. Top with pumpkin seeds, cheese, and cilantro.