Place tomato slices, garlic and other herbs into a clean, sterile 16-ounce glass jar until about 3/4 full.
Dissolve sea salt in water to create brine solution. Stir until salt is dissolved. Add vinegar, if using.
Add lemon juice to the mixture, if using.
Pour liquid in jar to cover tomatoes and herbs. Add more filtered water if necessary, so you only leave about an inch of room at the top.
Close the jar and leave on your counter for 7–10 days (or longer if you prefer) until naturally pickled by fermentation. Unless you are using an airlock lid, loosen the lid a little every two days to let built-up carbon dioxide out.
Or, if using vinegar for speed pickles, refrigerate for about an hour until chilled. (Better if left to marinate longer.)