Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce.

In a small pot, combine rice, 1¼ cups water (2¼ cups for 4 servings), and a pinch of salt. Bring to a boil, then cover and reduce heat to low. Cook until rice is tender, 15-18 minutes. Keep covered off heat until ready to use in Step 4.

While rice cooks, trim and halve radishes lengthwise; thinly slice crosswise into half-moons. Trim and halve cucumber lengthwise; thinly slice crosswise into half-moons. Trim and peel carrots; using a peeler, shave carrots lengthwise into ribbons, rotating as you go, until you get to the core. Discard core.

In a small bowl, combine vinegar, ½ tsp sugar (1 tsp for 4 servings), and a pinch of salt; stir in radishes and cucumber. Refrigerate until ready to serve.

Heat a drizzle of oil in a large, preferably nonstick, pan over medium-high heat. Add carrots; season with salt and pepper. Cook, stirring occasionally, until slightly softened, 1-2 minutes.

Stir in spinach; season with salt and pepper. Cook, stirring occasionally, until carrots are tender and spinach has wilted, 1-2 minutes more. Turn off heat; transfer to a plate. Wipe out pan.

Heat a drizzle of oil in pan used for veggies over medium-high heat. Add beef*; season with salt and pepper. Cook, breaking up meat into pieces, until browned and cooked through, 4-6 minutes.

Reduce heat to medium. Add bulgogi sauce and stir to coat. Cook, stirring occasionally, until sauce has slightly reduced, 1-2 minutes. 

Fluff rice with a fork. Stir in half the sesame oil (all for 4 servings). 

Arrange half the seaweed sheets in an even layer on a baking sheet (it’s OK if they overlap a bit). Toast on top rack until warm and lightly crisped, 1-2 minutes. Let cool for 1 minute, then cut into quarters.

Using your hands, crumble remaining seaweed sheets into a small serving bowl.

Carefully press rice into an 8-by-8-inch baking dish (9-by-13-inch baking dish for 4 servings) in an even layer. (TIP: Coat baking dish with nonstick cooking spray before adding rice.) Top with beef and smooth out in an even layer with a rubber spatula. Spread carrots and spinach in an even layer atop beef. Bake casserole on top rack until warmed through, 2-3 minutes.

Evenly top with pickled radishes and cucumber (draining first). 

Drizzle casserole with spicy mayo and top with sesame seeds and as much crumbled seaweed as you like. Serve family style directly from baking dish, with toasted seaweed sheets on the side. TIP: Add a spoonful of casserole to a seaweed sheet and eat it all in one bite!