They are really easy - 3 steps
1. Peel onions (hardest bit)
2. Brine onions (put in saltwater for a day) (you don't even need to this if you can't be bothered)
3. Put onions in jar with vinegar (and spices if you want)


INGREDIENTS

• 100g of salt to 1 litre of water.
• For 1 to 1½ kg of onions. 
• 1 litre vinegar
• Spices - try whatever

>>Heat the water and salt together until salt is dissolved. Allow to cool before placing peeled onions into the solution. The onions should be left in the brine for 24 hours then pickle

PICKLING

• Allow onions to cool and put in jar
• Cover with vinegar
• lid jar

Done! In this I used rosemary and black pepper and cumin seeds to spice it up a bit.