Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 450 degrees. Wash and dry produce.

Cut broccoli into bite-size pieces if necessary. Trim and quarter mushrooms (skip if your mushrooms are pre-sliced!). Core, deseed, and dice bell pepper into ½-inch pieces. Quarter lemon. Trim scallions, then cut crosswise into ½-inch pieces. Place skewers in a shallow dish and cover with water to soak (this helps prevent the skewers from burning!).

In a small pot, combine rice, 1¼ cups water (2½ cups for 4 servings), and a pinch of salt. Bring to a boil, then cover and reduce to a low simmer. Cook, covered, until rice is tender, 15-18 minutes. Keep covered off heat until ready to serve.

While rice cooks, heat a small, dry pan over medium-high heat. Add sesame seeds and cook, stirring, until golden brown and fragrant, 2-4 minutes. Transfer to a plate.

Toss broccoli, mushrooms, and half the bell pepper on a baking sheet with a large drizzle of oil, garlic powder, salt, and pepper. Roast on top rack until browned and tender, 15-20 minutes. (For 4 servings, divide veggies between 2 baking sheets; roast on top and middle racks, swapping rack positions halfway through.)

Meanwhile, in a medium bowl, combine katsu sauce, sweet soy glaze, half the soy sauce, and juice from one lemon wedge (two wedges for 4). Set yakitori sauce aside.

While veggies roast, pat steak* dry with paper towels and cut into ½-inch pieces.

Carefully thread steak, scallions, and remaining bell pepper onto skewers, alternating ingredients (you should have 6-8 skewers; 12-16 skewers for 4 servings). Season generously all over with salt and pepper.

Heat a drizzle of oil in a large pan (or grill pan) over medium-high heat. Working in batches, add steak skewers in a single layer and cook until browned and cooked through, 3-5 minutes per side. In the last 2 minutes of cooking, brush a thin layer of yakitori sauce onto skewers.

While skewers cook, place 2 TBSP butter (4 TBSP for 4 servings) in a second medium microwave-safe bowl. Microwave on high until melted, 25-30 seconds. Add remaining soy sauce and juice from one lemon wedge (two wedges for 4) and stir to combine.

Fluff rice with a fork and stir in sesame seeds. Season with salt and pepper. Add roasted veggies to bowl with soy butter and toss to coat.

Divide rice between plates. Top with veggies and steak skewers. Drizzle with remaining yakitori sauce. Serve with remaining lemon wedges on the side.