Step 1

Place the garlic, vinegar, brown sugar, butter, soy sauce, salt, and pepper in a large bowl and whisk to combine.

Step 2

Trim the mushroom stems, then halve any mushrooms that are larger than 1 inch in diameter. Add the mushrooms to the marinade, toss to combine, and let marinate at room temperature for 30 minutes. If using wooden skewers, soak them in water while the mushrooms marinate.

Step 3

Prepare an outdoor grill for medium-high, direct heat. Once hot, scrape the grill grates if needed to remove any lingering grit or debris.

Step 4

Thread the mushrooms onto the skewers, grouping similar-sized mushrooms together on the same skewers and spacing them about 1/2-inch apart. Place the skewers on a baking sheet to transport to the grill. Reserve the remaining marinade left in the bowl.

Step 5

Place the mushrooms in a single layer on the grill over direct heat. Grill uncovered, flipping once, until tender, 5 to 7 minutes per side. Transfer to a large plate or baking sheet. Remove the mushrooms from the skewers and place in the bowl with the remaining marinade. Top with the parsley and toss to combine. Serve immediately.