Copycat White Castle Sliders with Onions and Pickles

Why You’ll Love This Recipe

• True-to-memory onion-steam flavor thanks to rehydrated minced onions and no-flip patties.
• Ultra-thin beef with signature 5-hole pattern for fast, even cooking.
• Simple grocery list and stovetop-friendly method—no special tools required.
• Perfect for parties: make-ahead patties cook in minutes.

Grocery List

• Produce: Dehydrated minced onion (or 2 medium yellow onions finely minced as a backup)
• Dairy: American cheese slices (optional)
• Pantry: 80/20 ground beef, slider buns, dill pickle chips, yellow mustard, kosher salt, black pepper, neutral oil or beef tallow

Full Ingredients

Onion Bed (authentic-style)

• 1 cup dehydrated minced onion
• 1 1/2 cups very hot water (for soaking)
• Pinch kosher salt

Beef Patties

• 1 lb (454 g) 80/20 ground beef
• 1 tsp kosher salt
• 1/2 tsp freshly ground black pepper

Buns & Toppings

• 12 soft slider buns
• 24 dill pickle chips
• 6 slices American cheese, halved (optional)
• Yellow mustard (optional)
• 1 tsp neutral oil or beef tallow for the griddle

Step-by-Step Instructions

Step 1: Hydrate the onions

Add the dehydrated minced onion to a bowl and pour in 1 1/2 cups very hot water. Stir and let stand for 15 minutes until plump and juicy. Season with a pinch of salt. Reserve the soaking liquid—it becomes your flavorful steaming water.

Step 2: Make ultra-thin patties and punch the holes

On a parchment-lined sheet pan, press the beef between two sheets of parchment into a very thin slab about 1/8 inch thick. Use a ruler and knife or bench scraper to cut twelve 2 1/2-inch squares (about 0.9–1.0 oz each). Using a sturdy straw, chopstick, or the tip of a 1/4-inch piping nozzle, punch 5 holes in each patty in a “5-dice” pattern. Keep holes open (don’t close them with your fingers). Slide the pan into the freezer for 10–15 minutes to firm up for easy handling.

Step 3: Preheat the griddle and build the onion bed

Heat a large flat griddle or 12-inch skillet over medium-high (375°F if using an electric griddle). Lightly film with neutral oil or beef tallow. Working in batches (6 sliders at a time), spread about 3/4 cup of the rehydrated onions into a thin, even layer where the patties will sit. Sprinkle 2 tablespoons of the onion soaking liquid over the onions to create steam.

Step 4: Steam-griddle the patties (no flip)

Place patties hole-side up directly onto the onion bed. Season the tops lightly with a pinch of salt and pepper if desired. Cover with a large lid or inverted sheet pan to trap steam. Cook 2–3 minutes; the onions will bubble, the beef will turn opaque through the holes, and the underside will gently brown while the top steams. Do not flip.

Step 5: Steam the buns and melt the cheese

If using cheese, place a half-slice on each patty. Set a bottom bun directly on each patty (touching the cheese or meat), and place the bun tops cut-side up along the edge of the pan to warm. Cover again and steam 1–2 minutes more, until the buns are soft and warm and the beef reaches 160°F internally.

Step 6: Assemble and serve immediately

Using a wide spatula, scoop each patty with a tangle of onions onto the warmed bottom buns. Add two dill pickle chips and a small stripe of yellow mustard if you like. Cap with the top buns and serve right away while steamy and tender.

Pro Tips

• Use dehydrated onions for the most authentic flavor and texture; their soaking liquid is the perfect steamer.
• Weigh patties to 0.9–1.0 oz and keep them 1/8 inch thick so they cook through in minutes without flipping.
• Keep the five holes open; they’re key to letting onion steam rise and cook the patty evenly.
• Don’t skimp on the lid—trapping steam is what softens the buns and infuses that signature onion aroma.
• Work in quick batches so everything stays hot and steamy; sliders are best eaten immediately.

Variations

• Fresh-onion version: Finely mince 2 medium yellow onions, rinse briefly, drain well, and use 2 tablespoons water per batch to create steam.
• Cheeseburger sliders: Use American cheese for the classic melt, or try white American for a slightly sharper note.
• Spicy onion sliders: Mix 1/2 teaspoon cayenne or add pickled jalapeños under the pickles for gentle heat.

Storage & Make-Ahead

Form and hole-punch patties up to 24 hours ahead; keep covered and chilled, or freeze on parchment then store in a zipper bag for up to 1 month. Rehydrated onions keep 3 days refrigerated in a sealed container (with soaking liquid). Assembled sliders are best fresh; leftovers can be wrapped and refrigerated up to 1 day. Reheat by re-steaming in a covered skillet with 1–2 tablespoons water over medium heat for 2–3 minutes until hot and soft—avoid microwaving, which can toughen the buns.

Nutrition (per serving)

Approximate per slider, with pickles and mustard: 190 calories; 9 g fat; 17 g carbohydrates; 11 g protein; 380 mg sodium. With half-slice American cheese: about 220 calories; 12 g fat; 17 g carbohydrates; 12 g protein. Values will vary based on bun brand and cheese.