Yucatecan Grilled Catfish with Pickled Red Onions

Description
A Catfish recipe.

Ingredients
For the Pickled red onions: For the Achiote-Marinated Catfish:
 * 1 quart water, plus more as needed
 * 2 small red onions, sliced 1-inch thick
 * 2 teaspoons Sugar
 * 1 teaspoon dried oregano, preferably Mexican
 * 1/2 teaspoon freshly ground pepper
 * 1/2 teaspoon ground cumin
 * 1/2 teaspoon salt
 * 4 garlic cloves, halved
 * 2/3 cup cider vinegar or lime juice
 * 1 tablespoon achiote seed (see Note)
 * 1 teaspoon freshly ground black pepper
 * 1 teaspoon ground cinnamon
 * 1 teaspoon ground coriander
 * 1 teaspoon dried oregano, perferably Mexican
 * 1/4 teaspoon ground cloves
 * 1/2 teaspoon ground cumin
 * 5 large garlic cloves
 * 1 teaspoon salt
 * 3 tablespoons cider vinegar or lime juice
 * 6 U.S. Farm-Raised Catfish fillets
 * olive oil for brushing
 * For garnish: cilantro sprigs

Directions

 * 1) To prepare the pickled onions, bring 1 quart of water to a boil in a medium saucepan.
 * 2) Add onions and cook for 45 seconds.
 * 3) Drain onions and rinse under cold water.
 * 4) Place onions in a non-corrosive bowl and add Sugar, oregano, pepper, cumin, salt, garlic and vinegar or lime juice and stir to combine.
 * 5) Add enough water to the bowl to make the pickling liquid barely cover the onions.
 * 6) Cover and refrigerate for several hours, preferably overnight.
 * 7) To prepare the marinade, pulverize the achiote seeds as finely as possible in a spice grinder.
 * 8) Add the pepper, cinnamon, coriander, oregano, cloves and cumin and pulse the grinder on and off a few times to combine the spices.
 * 9) Place in a small bowl and set aside.
 * 10) Finely chop the garlic.
 * 11) Sprinkle salt over garlic.
 * 12) Using the flat side of a heavy chef's knife, mash and smear the garlic and salt mixture, working it back and forth on the cutting board until it forms a paste.
 * 13) Add the garlic paste along with the vinegar or lime juice to the bowl with the spice mixture and mix until thoroughly combined.
 * 14) Spread about a teaspoon of the marinade over each side of the Catfish fillets (there may be a little marinade left over).
 * 15) Place the fillets on a sheet pan, cover with plastic wrap and refrigerate for 1 to 2 hours.
 * 16) About 1 hour before serving, prepare a charcoal fire for grilling and let it burn until the coals are hot.
 * 17) To grill the marinated fillets, brush them with a little olive oil and place on the grill over the hottest part of the fire.
 * 18) After about 30 seconds, turn the fillets 90 degrees and grill on the same side for 30 seconds longer.
 * 19) Move the fillets to a cooler part of the fire and cook for 2 minutes longer on that side.
 * 20) Turn the fillets over and cook for 3 to 4 minutes on the other side or until flakes easily when tested with a fork.
 * 21) Serve the Catfish on warm plates topped with pickled red onions and a sprig of cilantro.