Prepare the garlic scapes by trimming off the tough ends and any flower buds. Roughly chop the remaining scape into manageable pieces.

In a food processor, combine the chopped garlic scapes, finely diced red bell pepper, and finely diced red onion. Pulse until finely minced but not puréed.

Add the fresh lemon juice, olive oil, Dijon mustard, salt, and black pepper to the food processor. Pulse again until well combined and the mixture resembles a relish.

Taste and adjust seasoning as needed, adding more salt, pepper, or lemon juice if desired.

Transfer the relish to a clean jar or serving dish. For best flavor, let it sit for at least 15-30 minutes at room temperature before serving to allow the flavors to meld.

Garnish with fresh chopped parsley, if using, before serving.