Combine all the ingredients except the oil, vinegar and water to a large bowl and mix together well, ensuring all the herbs and spices (especially the salt) are distributed evenly.
Allow to rest for 30 minutes.
Bring the vinegar and water to the boil, add to the other ingredients and mix well. This helps to soften the taste of the onion and garlic.
Allow to rest for 30 minutes.
Add the oil and mix well. If the liquid part doesn't cover the ingredients add oil water and vinegar in a 2:1:1 ratio to cover them.
Transfer to an air-tight container and refrigerate overnight at least, or better, for a few days.
When needed, remove from the refrigerator about 30 minutes ahead of time to allow the oil to thin out again. Stir well and serve.