Prepare the garlic scapes: Wash the scapes thoroughly. Trim off the tough bottom ends and the remainder of the flower bud if present. Cut the scapes into uniform 2-inch pieces.

Sterilize your jar: Make sure your quart-sized canning jar and lid are clean. If you prefer a longer shelf life, can the jars using a hot water bath method (not detailed here, but recommended for preservation). For refrigerator pickles, a simple wash is sufficient.

Pack the jar: Place the optional whole garlic cloves, mustard seeds, and peppercorns into the bottom of the prepared jar. Firmly pack the 2-inch pieces of garlic scapes vertically into the jar.

Make the brine: In a small saucepan, combine the water, white vinegar, kosher salt, and sugar. Bring the mixture to a boil over medium-high heat, stirring occasionally until the salt and sugar are completely dissolved. Remove from heat.

Pour and seal: Carefully pour the hot brine over the packed scapes in the jar, ensuring the liquid fully covers the scapes. Leave about 1/2 inch of headspace at the top. Tap the jar gently to release any trapped air bubbles.

Cool and refrigerate: Allow the jar to cool on the counter for about 30 minutes. Once cool, seal the jar tightly with the lid and transfer to the refrigerator. Allow to pickle for at least 24 hours before tasting, although they are best after 1 week.