Prep the scapes. Trim any dried or yellowing tips. Cut the scapes to fit your jars — you can leave them in their curled shape and coil them in (this looks great but takes a bit more effort to pack), or cut them into 3–4 inch straight lengths for easier packing. I usually do a mix: curls in one jar, cut pieces in the other.
Pack the jars. Divide the spices between the two clean pint jars — half the dill seed, pepper flakes, and black pepper in each. Pack the scapes in tightly. They'll compress more than you expect, so really get them in there.
Make the brine. Combine the vinegar, water, and salt in a small saucepan over medium heat. Stir and bring to a boil, just until the salt fully dissolves. Remove from heat.
Fill the jars. Pour the hot brine over the packed scapes, leaving about ½ inch of headspace. Tap the jars gently on the counter to release any air bubbles. The scapes should be fully submerged.
Cool and refrigerate. Let the jars cool uncovered for about 30 minutes, then seal and refrigerate. Give them at least 5 days before opening — a full week is better. The flavor deepens noticeably over the first two weeks.