Easy + Inexpensive 5-Ingredient Bean Soup

bacon, diced

large Spanish onion, finely diced

medium carrots, finely diced (about 2 cups)

ribs celery, finely diced (about 2 cups)

salt and pepper

garlic, minced (optional)

great northern beans or cannellini beans, soaked overnight* and drained

water (8 cups)

Parmesan cheese rind (optional)