You want to keep the asparagus crisp-tender here. Start with your leeks and cook until the white parts are starting to turn translucent, then add your asparagus and cook until it’s starting to soften.
The base layer of the galette is a cheesy mixture packed with dill and lemon zest. The aim is to mash the ingredients together until you have a chunky paste, not a smooth mixture. That adds a better texture to the finished dish.
Sprinkling the edges of the pastry with sesame seeds before baking adds even more texture to the final dish. Just be sure to brush the pastry with soy milk first, which will ensure the seeds stick once baked.