Melt 1 tablespoon butter in a large skillet or frying pan over medium heat.  Place top and bottom of telera bun, cut side down. Fry both sides until edges are golden brown.  Repeat with remaining buns and butter.

On a working surface, spread mayonnaise on bottom halves of buns.  Top with pickled jalapeño slices and queso fresco.  Place avocado slices on top half of bun.  Close sandwich and enjoy!