Cut and juice limes into container that can be sealed. I always use a lime squeezer.

Finely dice a medium sized red onion. Add chopped onion to lime juice, cover and refrigerate for at least 20 minutes.  There should be enough lime juice to cover the chopped onion. The signature ceviche taste comes from the onion 'cooking' in the lime juice.

Cut cauliflower florets into small pieces and place in bowl, add enough water to cover them and place  paper towel over the bowl.  Microwave 4-5 minutes.  Cool cooked cauliflower before mixing with other ingredients.

Chop mango into squares. I slice the mango from the top in quarters, there should be an 'x' at the top.  Then I  peel the skin off, if it's ripe enough.   On the 'meaty' sides I slice horizontally then vertically, then I cut it from the top down creating little mango squares.  This sounds more complicated than it seems but I promise it's not!

Combine the onion and lime juice mixture with the chopped mango, cooled cauliflower, diced tomatoes and chopped cilantro in bowl. 

Add salt and salsa as needed to get desired taste and consistency. 

Serve on tostadas or with chips.