Step 1: Cook Potatoes
Step 2: While potatoes are boiling, in a pan, combine vinegar, sugar, and peppercorns. Bring to a boil and stir to dissolve sugar.
Step 3: Place onion slices in hot vinegar mixture and let sit for 10 minutes. Then drain slices and transfer to a place in order to cool down.
Step 4: Remove flesh off potatoes and transfer to a bowl. Cut potatoes into slices.
Step 5: Add black pepper and salt, mash potatoes until creamy.
Step 6: Divide potato filling among four tortillas.