Before starting, wash and dry all produce. Lightly oil the grill. While you prep, preheat the grill to 500°F over medium-high heat. Thinly slice green onions.Add mayo and half the green onions to a small bowl. Season with salt and pepper, then stir to combine. Set aside. Cut sweet potatoes lengthwise into 1/2-inch thick slices.Add sweet potatoes, half the garlic salt and 1 tbsp (2 tbsp) oil to a medium bowl. Season with pepper, then toss to coat.Combine ketchup and brown sugar in another small bowl. (NOTE: This is your glaze.)

Add breadcrumbs, Worcestershire sauce, remaining green onions, remaining garlic salt and 2 tbsp (4 tbsp) milk to a large bowl. Season with pepper, then stir until milk is absorbed. Crumble in beef and pork mix, then combine.Form mixture into two 5-inch-wide patties (4 patties for 4 ppl).

Add sweet potatoes to one side of the grill, then reduce heat to medium. Close lid and grill, flipping once, until grill-marked and tender, 14-16 min.

Meanwhile, add patties to the other side of the grill. Close lid and grill patties, carefully flipping once, until cooked through, 4-5 min per side.** Spread glaze (from step 1) over tops of patties. Close lid and grill until glaze is warmed through, 1-2 min.

Halve buns. When sweet potatoes and meatloaf patties are almost done, add buns to grill, cut-side down. (NOTE: Don't overcrowd your grill! Toast buns once sweet potatoes and patties are done if there isn't enough space on the grill.)Close lid and grill until toasted, 1-2 min. (TIP: Keep an eye on buns so they don't burn!)

Spread some green onion mayo on bottom buns. Spread any remaining glaze on top buns. Stack bottom buns with spring mix, meatloaf patties and crispy shallots. Close with top buns. Divide burgers and grilled sweet potatoes between plates. Serve remaining green onion mayo alongside for dipping.