Heat oven to 200C/180C fan/gas 6. Simmer the beans and tomatoes in a pan for 15 mins, then season.
Meanwhile, grease four holes of a muffin tin with oil. Line each with a tortilla, making a cup, and fill with a ball of foil. Bake for 5 mins until lightly crisped. Remove the foil, divide the bean mix between the tortilla cups and serve with the green salad.