Adjust racks to top and middle positions and preheat oven to 350 degrees. Wash and dry produce.

Cut potatoes into ½-inch-thick wedges. Halve, peel, and dice onion into ¼-inch pieces. Drain and roughly chop pickle.

In a medium bowl, combine BBQ sauce, ketchup, stock concentrates, cornstarch, and 2 TBSP water (4 TBSP for 8 servings).

Place 4 TBSP butter (8 TBSP for 8) in a separate medium microwave-safe bowl; microwave until melted, 30-60 seconds.

Toss potatoes on a baking sheet with a large drizzle of oil, salt, and pepper. Roast on top rack until browned and tender, 40-45 minutes.

While potatoes roast, heat a drizzle of oil in a large pan (large high-sided pan or pot for 8 servings) over medium-high heat. Add onion; cook, stirring, until softened, 4-5 minutes.

Add turkey*; season with Southwest Spice Blend, salt, and pepper. Cook, breaking up meat into pieces, until browned, 3-5 minutes.

Add BBQ sauce mixture. Cook, stirring, until sauce has thickened and turkey is cooked through, 2-3 minutes more. Taste and season with salt and pepper.

Turn off heat. Stir in pickle.

Carefully separate top slider buns from bottom slider buns (keep top buns connected and bottom buns connected). Arrange bottom buns in a single layer in a 9-by-13-inch baking dish (two 9-by-13-inch baking dishes for 8 servings).

Evenly sprinkle cheddar over bottom buns. Top with BBQ turkey. Sprinkle with Monterey Jack. Close with top buns to form sliders.

Brush melted butter over sliders. Cover baking dish tightly with foil. Bake on middle rack for 20 minutes.

Serve sliders and potato wedges family style with ranch dressing on the side for dipping.