Using a food processor, pulse cauliflower heads into a coarse blend resembling fine mince.
Heat 1 tbsp of oil in a pan. Add chopped onion and stir fry it for a minute.
Add chopped tomatoes. Stir fry it another for 3 to 4 minutes until the tomatoes are slightly tender. Add Cauliflower mince, beans and taco seasoning at this stage. Stir fry them only for 2 to 3 minutes. Don't over cook them as cauliflower will realise moisture. Remove it from fire and add chopped capsicums ( red and green) and garnish it with coriander.
Check the seasoning and add more salt if needed. The filling is now ready.
Check the packet instructions and cook the tacos accordingly. Arrange sour cream in a bowl, mash avocado, squeeze in few drops of lime juice, season it with salt and pepper. Keep it aside in a bowl. Arrange soft and hard taco shell in a plate. Fill in the cauliflower mince in the tacos, Top it with finely shredded cabbage, cheese. It is ready to serve. Enjoy with sour cream and guacamole (avocado mash).