Make the leche de tigre: 

• Add onion, cucumber, water, and shrimp to a blender and blend until smooth and homogenous. 
• Strain through a sieve.
• Season the liquid with Forager’s Vinaigrette, lime juice, and salt.

Make the ceviche:  

• Blanch the shrimp in a pot for no longer than 1 minute and cool them down in ice water.
• Add the shrimp, cucumber, avocado, onion, and Summer Pickles to a bowl and mix with the leche de tigre.
• Let the ceviche marinate in the fridge for 30 minutes before serving with tostadas and cilantro.