How to: easy shrimp ceviche

I've always loved seafood! When I say love, I mean LOVE with capital letters!!! I'm a big eater but not a great cooker but sometimes I can do wonders with my hands. So here's my take on an easy ceviche.

 You will need:

• About 20 shrimps, peeled and deveined (I am using 21/25, but I find using the 26/30 better because the shrimps won't be as thick) 
• 1/3 of a big red onion
• A pinch of salt, pepper and sodium 
• A teaspoon of fish sauce (you can add more later according to your taste)
• 1/3 of a cup of cilantro (you can put as much as you like, but not too much) 
• 2 big citrus (I've actually use 2 and a half because I like it sour)