Mongo Guisado (Mung Bean Soup)

INGREDIENTS

• 1/2 pound raw mung beans
• 2 cups water
• 2 tablespoons olive oil
• 1 onion, chopped
• 2 cloves garlic, minced
• 1/4 pound boneless pork loin, cut into 1-inch cubes
• salt and ground black pepper to taste
• 1/4 pound peeled and deveined prawns
• 1 small tomato, diced
• 3 cups chicken broth, or more as needed
• 1/2 pound fresh spinach leaves