Step 1

Remove leaves and trim stem of cauliflower, leaving core intact. Place cauliflower, core side down, on a work surface. Starting at the midline of the cauliflower, slice from top to bottom into four ½" "steaks" (reserve any florets that break loose).

Step 2

Prepare a grill for medium-high heat and lightly oil grate. Drizzle cauliflower steaks, florets, and scallions with 4 Tbsp. oil; season with salt and pepper. Grill scallions, turning occasionally, until charred in spots, about 2 minutes. Grill cauliflower steaks until tender and charred in spots, 8–10 minutes per side. Grill any loose florets in a grill basket, tossing often, until cooked through, 5–7 minutes.

Step 3

Blend ginger, garlic, cilantro, lime juice, and remaining 2 Tbsp. oil in a food processor, thinning with water if needed, until sauce is the consistency of yogurt; season with salt.

Step 4

Arrange cauliflower and scallions on a platter. Sprinkle with gochugaru and sesame seeds and drizzle with sesame oil. Serve with cilantro sauce alongside.