Knead the flour, Greek yogurt, salt, and frozen butter into a smooth dough. Fold each end of the dough toward the middle, wrap it in plastic wrap, and refrigerate the dough for 45 minutes.
Preheat the oven to 400°F.
Remove the dough from the fridge, roll it out into a rectangle, cut off any excess dough, and place the rectangle on a sheet pan lined with parchment paper.
Spread the Dijon mustard down the middle of the dough and cover it with half of the ham slices, then half of the Swiss cheese slices, then the other half of the ham slices, and finally the remaining Swiss cheese slices. Place the feta cheese on top of the layered ham and cheese slices and spread the garlic & herb sauce over it.
Make evenly-spaced diagonal incisions in the dough on either side of the ham and cheese block.
Cut the asparagus tips to size – they should be about 2-3 inches long, including the head. Now braid the dough as shown in the video and place an asparagus tip in each dough pocket on both sides.
Brush the dough with the egg white, sprinkle sea salt on top, put the pan in the oven, and cook the ham and cheese asparagus braid for 15-20 minutes.