Boil the water and cook the cauliflower with a little salt and the flour. When the cauliflower is tender (but not too tender) let it cool and chop it really fine. Dice the onion in very small pieces and add the juice of the lemon, let it rest while dicing the other vegetables as small as you can. Mix all the vegetables with the onion and cauliflower. Add salt to taste and the oil. Mix again and let it rest in the fridge for an hour before you serve it. I like to serve it with avocado and ketchup, but it's great alone. You can eat it with tortilla chips too.