Prep strawberries. Wash the strawberries, hull, and cut them in half. If they are very large, you might have to cut them into quarters.
Sterilize jar. Make sure your quart jar is properly sterilized before using it to prevent any bacterial growth.
Make pickling liquid. In a saucepan, combine balsamic vinegar, water, sugar, and salt. Bring to a boil, stirring to dissolve the sugar and salt.
Add spices. Once the sugar and salt have dissolved, add the peppercorns, fresh thyme, cinnamon stick, and lemon zest. Reduce the heat and simmer for 5 minutes to infuse the flavors.
Assemble. Place the prepared strawberries into the sterilized quart jar. Carefully pour the hot pickling liquid over the strawberries in the jar, making sure the spices are distributed evenly. Leave about a half-inch of headspace at the top of the jar.
Seal and cool. Close the jar tightly with its lid. Let it cool to room temperature. Once cooled to room temperature, refrigerate the jar. Let the strawberries pickle for at least 4 hours before using them for the best flavor.
Serve. Enjoy your pickled strawberries with salads, cheeses, or as a unique garnish for drinks and desserts.