Bring a medium pot of water to a boil. Peel the broccoli stems and slice them into 1/2-inch-thick coins (or oddball shapes--just keep them all about the same size). Blanch them in the boiling water until fork-tender, 2 to 4 minutes. Cool them in ice water; drain.
Bring the vinegar, salt, sugar, pickling spice, bay leaf, lemon zest and juice and 1 cup water to a boil in a small saucepan. Pour over the broccoli and let cool. Refrigerate for at least 4 hours.