Wash the cherry tomatoes and pull off the stems. You do not need to prick them. The brine works its way in through the stem scar as they sit, that little opening where the stem was is all it needs.
Combine the water, rice vinegar, sugar, and garlic salt in a small pot. Bring to a boil, stirring until the sugar and salt fully dissolve. Keep it hot, the heat is what drives the suction in the next step.
Pack the tomatoes into clean, heat-safe jars. Canning jars (Ball or Mason style) are built to take boiling liquid. Avoid thin or decorative glass, which can crack from the sudden heat, and run cold jars under warm water first so the hot brine does not shock them. Pour the hot brine over the tomatoes while it is still steaming, filling until they are fully submerged. Seal the lids tight.
Right after sealing, flip each jar upside down so the brine reaches the tomatoes at the top. Let the jars cool this way. As they cool, the air inside each tomato contracts and pulls the brine in through the stem scar. Once cooled to room temperature, about 1 to 2 hours, turn the jars right side up (in case a lid leaks) and move them to the fridge. They are ready by the next morning. Keep them refrigerated the whole time, this is a fresh pickle, not a shelf-stable canned one.
CHEF'S NOTE
Pour the brine on hot. The heat expands the air inside the tomatoes, and the cooldown creates the vacuum that pulls the brine in through the stem scar. Cold brine skips that suction and barely seasons the inside.
No need to prick them. Pull the stems and the stem scar is the opening the suction draws through. The rest of the skin is sealed and waxy.
Flip the jar after sealing. Inverting it right after you lid it makes sure the brine coats the tomatoes at the top while everything cools. Turn it right side up before it goes in the fridge in case a lid leaks.
Keep them submerged. Fill the jar with brine until every tomato is under the liquid. Top off at the same ratio if any are poking out.
Vinegar swaps (same 2 cups). Apple cider vinegar for a fruitier, rounder tang. Plain white vinegar for a sharper bite, add an extra 1 tsp sugar to balance it.
Sugar swaps (for the 1 tbsp). Brown sugar: 1 tbsp, straight swap. Honey: 1 tbsp, stir into warm brine so it dissolves. Stevia: start at about ¼ tsp and taste, it is far sweeter than sugar.
Garlic salt swaps (for the 1 tbsp). No Lawry's? Use 2 tsp kosher or table salt plus ½ tsp garlic powder. Or 2 tsp salt plus a smashed garlic clove. Plain salt alone (2 tsp) works too, you just get clean salt-and-vinegar tomatoes.
Make it spicy. Drop 1 sliced fresh chili, 1 tbsp chili crisp, or ½ tsp red pepper flakes into the jar.
Ready by morning. Overnight in the fridge is all they need. They keep up to 4 weeks, but they are best within the first 2.
