To prepare salsa sauce, heat boiled tomato puree in a non-stick pan.
Roughly chop basil leaves and add to pan. Add 1 teaspoon dried oregano, chilli flakes and salt, mix and cook for a minute. Add tomato ketchup and 1 tablespoon olive oil, mix and cook for a minute. Add fresh torn oregano, mix and cook for 2-3 minutes. Remove from heat and transfer into a bowl.
To prepare red kidney bean filling, heat remaining olive oil in another non-stick pan. Add celery and sauté for 30 seconds. Add tomatoes and sauté for a minute.
Add remaining dried oregano, chilli flakes, crushed peppercorns, salt and red kidney beans and mix well. Add chilli powder and mash the mixture using a masher. Add Mexican sauce, mix and cook for a minute and switch off the heat.
Arrange the taco shells on the table top. Put some iceberg lettuce, purple cabbage and red kidney bean filling in each taco. Top with some bell peppers, capsicum, salsa sauce, sour cream, and grated cheese. Serve immediately.