Pack the Jar: Wash your cherry tomatoes thoroughly and pat them dry. Pack the whole tomatoes into a clean 1-quart glass jar, tucking the halved garlic cloves, whole peppercorns, and fresh basil sprigs into the gaps between the tomatoes.
Heat the Brine: In a small saucepan, combine the water, white wine vinegar, sugar, kosher salt, and crushed red pepper flakes. Place the pan over high heat and stir frequently.
Dissolve: Cook just until the salt and sugar have fully dissolved into the liquid. Remove the pan from the heat just before the mixture reaches a full boil or simmer.
Pour & Seal: Carefully pour the hot liquid brine directly over the tomatoes in the jar, ensuring they are completely submerged. Secure the lid tightly.
Cool & Chill: Leave the sealed jar on the counter to cool completely to room temperature. Once cool, transfer it to the refrigerator to chill for at least 8 hours. For the ultimate flavor development, let them cure for a full 24 hours before your first taste.