
Rinse the onions under cold water and pat them dry. Trim off the root ends and about 4 inches off the tops of the green stems, then discard any wilted pieces. Coat the onions evenly with olive oil or lightly spray with cooking spray.
Heat a comal, cast-iron skillet, or grill pan over medium-high heat. Add the onions and cook until softened, lightly charred, and the bulbs feel tender when pressed, about 3 to 5 minutes per side. Try not to flip them too often so they have time to caramelize and develop color.
Remove from the heat and season with kosher salt. Squeeze fresh lime juice over the top, then add a few dashes of Jugo Maggi seasoning, soy sauce, or Worcestershire, if desired.
Serve immediately with carne asada or other grilled meats. You can serve them whole as a side or chop them up and add them to tacos.