Sterilise your jar (I used a 350ml sized jar) by washing in hot soapy water and drying in oven for 30 mins or by putting through a hot wash in dishwasher.
Wash and pat dry tomatoes and prick all over with a skewer or fondue fork (this is to let the pickling liquid get right inside them faster)
Pack tomatoes and sliced garlic into your jar.
Place all other ingredients in a non-reactive pan (stainless steel/enamel etc but not copper) and bring almost to the boil.
Let it simmer for 5 minutes then remove from heat.
Pour pickling liquid over the tomatoes and pop on the lid.
Store for 1 week before using to allow the flavours to mature.
This will keep for up to 6 months in the fridge.