Cook the bacon until really crisp. I bake mine in the oven for 20 to 25 minutes at 400 degrees F. Drain the cooked slices on a paper towel lined plate and pat dry.
Assemble your sandwich on the halved croissant. Spread 1 tablespoon Dijon mustard on the croissant, top with a large leafy green lettuce leaf followed by two slices of turkey breast, ¼ of the sliced avocado, ¼ of the purple onion and ¼ of the sliced cucumber. Top with the top half of the croissant.