Rinse 2 cups of black beans under cold water and pick out any debris. In a large stockpot, combine beans with 8 cups of water, 2 bay leaves, and 1 teaspoon salt. Bring to a boil over high heat, then reduce to medium-low and simmer for 60-75 minutes until beans are very tender.

While beans cook, slice 400g linguiça sausage into 1/4-inch rounds. In a large skillet over medium heat, cook sausage pieces until browned and crispy on edges, about 8-10 minutes. Remove and set aside, reserving 2 tablespoons of fat in the pan.

In the same skillet with reserved fat, add 2 diced onions and sauté for 5 minutes until softened. Add 4 minced garlic cloves and cook for 1 minute until fragrant. Add 1 teaspoon cumin and 1/2 teaspoon black pepper, stirring for 30 seconds.

Once beans are tender, remove bay leaves. Using an immersion blender, partially blend the beans directly in the pot until about half are smooth while leaving some whole beans for texture. Alternatively, transfer 3 cups of beans with liquid to a regular blender, blend until smooth, and return to the pot.

Add the sautéed onion-garlic mixture and cooked sausage to the bean pot. Stir well and simmer for 10 minutes to meld flavors. Taste and adjust salt as needed. If too thick, add water to reach desired consistency.

Ladle the caldinho into small serving cups or bowls. Drizzle each portion with 1 teaspoon olive oil and garnish with fresh chopped cilantro. Serve immediately while hot.