Cook and peel your shrimp. Cut into small pieces and then toss them into a large mixing bowl. (You can use precooked shrimp as well.)
Chop up the tomatoes, onion, cilantro, in addition to the avocado. Toss everything into the bowl as well.
Squeeze the lime(s) into your bowl.
Season with pepper and mix all the ingredients! (We're saving the avocado for last so it doesn't brown too soon.)
Place the bowl in the fridge to chill for about 45 min.
Once chilled, chop your avocado, add it in, and season with salt.
Grab your tostadas and spread some sour cream on them.
Top your tostadas with the mixed ingredients you just made.
Finally, drizzle each tostada with the hot sauce and enjoy!