Adjust rack to top position and preheat oven to 450 degrees. Wash and dry produce.

Cut potatoes into ½-inch-thick wedges. Halve, peel, and finely dice onion. Halve buns.

Toss potatoes on a baking sheet with a large drizzle of oil, salt, and pepper.

Roast on top rack until browned and tender, 20-25 minutes.

While potatoes roast, in a small bowl, combine mayonnaise and half the chimichurri.

Set aside until ready to serve.

Heat a drizzle of oil in a large pan over medium-high heat. Add onion; cook, stirring, until softened, 4-5 minutes.

Add beef*; season with salt and pepper. Cook, breaking up meat into pieces, until browned, 3-5 minutes. TIP: If there’s excess grease in your pan, carefully pour it out.

Add zesty ancho sauce and ketchup; cook, stirring, until sauce has thickened and beef is cooked through, 2-3 minutes. Taste and season with salt and pepper.

Turn off heat. Stir in Monterey Jack until melted, 30-60 seconds.

Toast buns until golden brown.

Spread buns with remaining chimichurri. Fill with as much zesty ancho beef as you like.

Divide sliders and potato wedges between plates. Serve with chimichurri mayo on the side for dipping.