In a large pan, heat oil and cook onion until soft 6-7 minutes. Add garlic and cook for a further 30 seconds. Add spices (cumin, paprika, oregano, coriander) and chilli powder (if using) and stir for another 30 seconds. Add red kidney beans and stir to coat well.
Stir in tomato puree, season with salt and pepper, then cover and bring to a gentle simmer for 10 minutes, stirring frequently.
In the meantime combine corn, tomatoes, reserved red onion and lime juice and set aside.
Heat corn tortillas as per instructions on the pack.
To serve: spoon the red kidney bean mixture into the tortillas, add salsa and toppings and enjoy!