In a soup pot, heat olive oil over medium heat. Add onion and cook until softened and translucent, stirring frequently. Add cumin, chili powder, and salt; cook and stir until fragrant, about a minute. Stir in black bean, salsa, lime juice, and vegetable broth. Bring to a boil. Cover and simmer for 10 minutes.

Transfer half of the soup to a blender and blend until smooth. Stir back into the soup. Garish with cilantro if desired.