In a large sauce pan with a tight fitting lid, bring water, vinegar,salt, peppercorns, and chili to a boil, uncovered, for 5 minutes.
Add shrimp and boil for 1-2 minutes, cover, remove from heat, and allow to stand for 8-10 minutes, until shrimp have turned pink. Strain shrimp and set aside to cool.
To make the chipotle cream, whisk together yogurt, chipotle pepper, lemon juice, and a pinch of salt in a small bowl. Set aside.
Heat tortillas in a dry skillet over high heat, flipping every 15-30 seconds, allowing them to brown a bit on each side.
To assemble the tacos, fill each tortilla with an even amount of cabbage, 2-3 pieces of shrimp, 1-2 slices of avocado, a sprinkle of cilantro, and a heaping spoonful of chipotle cream.