Shrimp Ceviche Lettuce Cups

Name: Shrimp Ceviche Lettuce Cups
Ingredients: 1/2 pound shrimp, peeled, tails off and deveined, butterflied and cut into pieces; 1/4 jalapeño (if you're adverse to heat, you can remove the seeds and ribs. I didn't because I liked the spice), plus more for garnish; 1/2 inch knob of fresh ginger, peeled; Small handful of cilantro, plus a few extra leaves for garnish; 1 garlic clove; Juice from 3 limes; Pinch of salt; 1 Persian cucumber, cut into a small dice; 1 shallot, minced; 1 head of butter lettuce, leaves torn and separated; 1/2 avocado, thinly sliced