In Mexico, one is generally served cebollas encurtidas with cochonita pibil (braised suckling pig) tacos. It’s is also an ideal topping for sandwiches of any variety. The onions keep for 3-4 weeks in the fridge.
Thinly slice the onions.
Carefully separate the slices into a large bowl.
Throw in 3 litres of boiling water.
After 15 seconds, remove from water. Let onions drain for 10 minutes.
Put the onions, spices, and salt in a bowl. Cover completely with white vinegar.
Mix and let rest for at least 30 minutes before serving.