- 1 (20 ounce) package 15-bean soup mix (seasoning packet not used)
- 2 tablespoons olive oil, or more as needed
- 1 large onion, diced
- 12 carrots, peeled and chopped, or more to taste
- 15 crimini mushrooms, sliced, or more to taste
- 7 stalks celery, chopped, or more to taste
- 6 leaves dinosaur kale, chopped
- 4 leaves red Swiss chard, chopped
- 3 large cloves garlic, minced
- 12 cups vegetable broth
- 2 bay leaves
- 1 teaspoon dried rosemary
- 1 teaspoon dried basil
- salt and ground black pepper to taste
- Place beans in a large container and cover with several inches of cool water; let stand 8 hours to overnight. Drain and rinse.
- Heat olive oil in a stockpot over medium heat; cook and stir onion until golden brown, 15 to 20 minutes. Add carrots, mushrooms, celery, kale, chard, and garlic; cook and stir until carrots and mushrooms are slightly tender, 5 to 10 minutes.
- Pour broth over vegetable mixture and bring to a boil; reduce heat and add bay leaves, rosemary, basil, salt, and pepper. Add beans and simmer soup until beans are softened, 1 1/2 to 2 hours.