Step 1

Heat oil in an Instant Pot or other electric pressure cooker on the Sauté setting. Add onion and cook, stirring occasionally, until beginning to turn golden brown around the edges, 6–8 minutes. Add garlic and cumin and cook, stirring constantly, 2 minutes. Add beans, quinoa, adobo sauce, 2 tsp. salt, and 7 cups water. Lock lid and cook soup on high pressure 45 minutes, then release pressure manually. Squeeze in juice from lime half; mix well. Taste and season soup with more salt if needed.

Step 2

Do Ahead: Soup can be made 2 days ahead. Let cool, then cover and chill. Soup will thicken; add up to 1 cup water before reheating over medium-low.

Step 3

While the soup is cooking, toss onion, vinegar, salt, sugar, and 4 tsp. water in a small bowl to combine. Chill until ready to use.

Step 4

To serve, ladle soup into bowls and top with pickled onions and other toppings of your choice.

Step 5

Do Ahead: Onion can be pickled 5 days ahead. Cover and keep chilled.