Peel and clean the shrimps, remove their heads and black strips if needed. Cut them along to create a butterfly cut or you could cut them completely.
Peel the cucumber, cut it in half, remove the seeds and cut it in half moons.
Blend lime juice, serrano peppers, coriander, salt and pepper. If you don´t like it too spicy you could remove the seeds from the serrano pepper before blending it, if you prefer it spicier leave the seeds and add more serrano pepper.
Place the shrimps in a bowl or a plate, cover them with lime and serrano pepper, mix and let it sit for 30 minutes in the fridge.
Afterwards, take the bowl out of the fridge, add cucumber and purple onion to the mix and stir.
Add, on top, El Chilerito Hot Spicy Sauce.
Season to taste (if needed) and serve with tostadas.
Note: The lime juice acts as a disinfectant for the shrimps, but if you are afraid of eating raw ahrimps, you could cook them first and then make this recipe as explained.