Prepare the Coating: In a bowl, mix flour, garlic powder, smoked paprika, salt, and pepper. Place beaten eggs in a separate bowl and breadcrumbs in another.
Coat the Mushrooms: Roll each mushroom in the flour mixture, dip in the egg, and coat with breadcrumbs. Repeat for double-coating if desired.
Fry the Mushrooms: Heat vegetable oil in a pan over medium heat. Fry mushrooms in batches until golden brown and crispy, about 2–3 minutes per batch. Drain on paper towels.
Make the Dip: In a small bowl, whisk together Dijon mustard, mayonnaise, honey, lemon juice, and chili flakes. Adjust seasoning to taste.
Serve and Enjoy: Arrange mushrooms on a platter and serve hot with the tangy mustard dip on the side.