Heat at least 2 inches of vegetable oil in a Dutch oven or other heavy-bottomed pot to 350°F. Working in batches, fry the wonton strips until golden, about 30 seconds, stirring so they cook evenly. With a slotted spoon or a spider, transfer the fried wontons to a paper towel-lined baking sheet to drain, and season lightly with salt. Set aside while you make the gravy.

In a medium bowl, combine the stock, wine, cornstarch, soy sauce, sesame oil, and 1/2 teaspoon of the pepper, and stir to mix well. Set aside.

Heat a large skillet or wok over high heat. When hot, add the 3 tablespoons vegetable oil. When the oil shimmers, add the onion, celery, and mushrooms, and season with a pinch of salt and a pinch of black pepper. Cook, tossing occasionally, until the vegetables are crisp-tender, 3 to 4 minutes. Transfer to a bowl and set aside.

Add the ground meat to the hot skillet and season with a pinch of salt and a pinch of pepper. Cook, stirring with a spoon to break up any clumps, until the meat is nicely browned, 2 to 3 minutes. Add the garlic and cook, stirring, for 1 minute longer. Stir the stock mixture, then add it all at once to the pan and cook, stirring, until the sauce comes to a boil and thickens enough to coat the back of a spoon, 2 to 3 minutes. Stir in the vegetables and, the chow mein noodle crips. Place the bottom half of the hamburger bun on a plate, spoon the finished mixture on top, and then top with the remaining bun.