Mixiote of Shrimp and Nopales

Light the grill and let burn down to a medium fire. In the meantime, bring a pot of salted water to a boil, add the nopales, and onion, and cook until just tender, about 3 minutes. Drain, rinse, put in a bowl and let cool. Add the recado and shrimp and toss well. Spread mixiote (or banana leaf or parchment) on a countertop and divide the shrimp mixture among them. Top each with an epazote leaf and then fold up into a tight square package. Wrap each package in aluminum foil. Put the bundles on the grill, cover grill and cook until the shrimp are cooked through, about 20 minutes. remove packages form foil and serve of their wrappers with avocado slices.