In a stockpot, heat 1 tablespoon oil over medium heat then add onions and cook and stir until softened and lightly browned, about 3-5 minutes. Add garlic and cook until softened, about 1 minute.
Push onions and garlic to one side and add remaining tablespoon oil; add sausage and cook and stir until lightly browned, about 3 minutes.
Add chicken broth, tomatoes, potatoes and salt; bring to a simmer and cook 5 minutes. Add beans and simmer until broth is slightly thickened and potatoes are soft when poked with the tip of a knife, about 20 minutes.
While soup is simmering, cut tortillas into 4 pieces then cut each piece into ½ inch wide strips. Heat vegetable oil in a small saucepan over medium heat. In batches, fry tortilla strips just until golden brown and crisp, about 1 minute; transfer to a paper to a paper towel to drain and sprinkle with salt.
Season soup with salt and pepper. Ladle into serving bowls and top with cilantro and tortilla strips.