Peel and deseed 1 medium-sized ripe papaya. Cut it into small cubes and set aside.
In a large bowl, combine 250 grams of cleaned and deveined shrimp with the juice of 4 fresh limes, 1 finely chopped green chili, 1 finely chopped small red onion, and a pinch of salt. Mix well and let it marinate for 15-20 minutes, until the shrimp turns pink and opaque.
Drain the excess lime juice from the shrimp mixture and add the cubed papaya, 1/4 cup of chopped fresh cilantro, and 1/4 cup of chopped fresh mint. Mix gently to combine all the ingredients.
Taste and adjust the seasoning with salt and pepper, if necessary.
Refrigerate the ceviche for at least 30 minutes before serving to allow the flavors to meld.
Serve chilled, garnished with additional cilantro and mint leaves, if desired.