Heat oven to 425°F. Brush a sheet pan with the vegetable oil.
Stir breadcrumbs, flour, salt, pepper, paprika, garlic, onion, oregano, baking powder, and sugar in a large bag.
Pat chicken dry and trim excess fat.
Whisk olive oil with Dijon. Toss or brush it over the chicken to lightly coat.
Add chicken to the bag in batches. Seal and shake until evenly coated.
Arrange coated pieces on the oiled pan, spacing them out.
Bake 22–28 minutes, flipping once, until golden and 165°F inside.
Rest 5 minutes before serving to keep juices in the meat.