Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce. Trim, peel, and cut carrots on a diagonal into 1/2-inch-thick pieces. Trim and slice scallion into 1-inch pieces. Trim green beans if necessary or trim and discard woody bottom ends from asparagus. (Save carrots for another use.)

Toss carrots and scallion on a baking sheet with a large drizzle of oil and brown sugar. Season with salt, pepper, and as much chili flakes as you like (we used 1/4 tsp for 2 servings, 1/2 tsp for 4). Roast on top rack until tender, 20-25 minutes. Swap in green beans or asparagus for carrots; roast 12-15 minutes for green beans or 10-12 minutes for asparagus.

Pat chicken* dry with paper towels; place between two large pieces of plastic wrap. Pound with a mallet or rolling pin until chicken is about 1/2 inch thick. Season all over with salt and pepper. Heat a drizzle of oil in a large pan over medium-high heat. Add chicken; cook until browned and cooked through, 3-5 minutes per side. Turn off heat; transfer to a plate and tent with foil to keep warm. Carefully wipe any burned bits out of pan if necessary (it’s okay to leave lightly browned bits in the pan—it gives flavor to the gravy you’ll make in the Step 5!). Reserve pan.

While chicken cooks, in a small bowl, combine cranberry jam and mirepoix paste.

Melt 1 TBSP butter (2 TBSP for 4 servings) in pan used for chicken over low heat. Sprinkle flour over melted butter; whisk to combine. Cook, whisking occasionally, until flour is lightly browned, 2-3 minutes. Stir in 1/2 cup water (1 cup for 4) and stock concentrate. Bring to a simmer and cook, stirring occasionally, until thickened and saucy, 2-4 minutes. (TIP: If gravy seems too thick, stir in water a splash at a time.) Taste and season with pepper. While gravy cooks, halve and toast buns.

Evenly spread bottom buns with cranberry spread. Place chicken on bottom buns. Top chicken with a thin layer of gravy. Close sandwiches. Divide sandwiches and spicy brown sugar carrots between plates. Serve with remaining gravy on the side for dipping. Chicken is fully cooked when internal temperature reaches 165°.