Place the serrano peppers, red peppers, celery, carrot, cauliflower and onion into a large bowl. Add the salt and mix well. Cover with cold water and allow the vegetables to brine for up to 12 hours, refrigerated.

Drain the vegetables in a colander, and rinse to remove excess salt.

Into each canning jar, put 1 bay leaf, 2 garlic cloves, a pinch of chili flakes and 1/4 teaspoon peppercorns.

Pack the jars with the vegetables, and add an oregano sprig to each jar. Shake the jars to settle the vegetables.

Measure the vinegar, water and salt in a saucepan. Heat until the salt is dissolved. Pour the hot liquid over the vegetables, leaving 1/2-inch headspace.

Top each jar with 1 tablespoon of the olive oil.

Make sure the rims of the jars are clean. Close the jars and submerge in boiling water for 20 minutes. Set jars on a dry towel to cool and finish sealing. See How to Safely Can Your Vegetables and Fruit for complete canning instructions.

Store in a cool dark place for at least 3 weeks before eating.