Preheat the oven to 400 degrees Fahrenheit. Lightly grease a non-stick baking sheet or line with parchment paper or aluminum foil.
In a medium skillet, toast the panko breadcrumbs over medium heat until lightly golden, stirring constantly. Remove from heat and set aside.
In a food processor, pulse the pretzels until coarsely ground. Place the crumbs in a shallow dish and mix with the panko breadcrumbs.
Wipe out the crumbs from the processor. Add the oil, mustard, honey, water, and vinegar and pulse until smooth. Season with salt and pepper to taste.
Pound the chicken with a mallet to even the thickness and season well with salt and pepper.
Set up a dredging station with the shallow bowl of breadcrumb mixture, add the flour to a large plate, and pour half of the dressing into a shallow bowl.
Dredge the chicken in the flour, then into the dressing, and lastly coat in the pretzels. Repeat with each chicken piece and place them onto the prepared baking sheet.
Bake for 16-25 minutes or until the chicken is cooked through. Serve with remaining honey mustard dressing.