Place each cauliflower head stem-side down on your cutting board. Slice vertically through the center to create two thick 'steaks' from the middle of each head, about 1 to 1.5 inches thick. The outer pieces will fall apart - save these for another use. You should get 4 intact steaks total.

In a small bowl, whisk together the olive oil, minced garlic, smoked paprika, cumin, and half the kosher salt. Let it sit for 5 minutes so the garlic infuses the oil.

Brush both sides of each cauliflower steak generously with the seasoned oil. Sprinkle the remaining kosher salt and all the black pepper evenly over both sides. Let them rest at room temperature while you heat the grill.

Heat your grill to medium-high, about 400-450 degrees F. Clean and oil the grates well. Place the steaks directly on the grill and cook undisturbed for 6-8 minutes until deep golden char marks appear. Flip carefully with tongs - they can be fragile - and grill the second side for another 6-8 minutes until the stems are tender when pierced with a knife.

Transfer the grilled steaks to a platter. Immediately drizzle with fresh lemon juice, scatter the lemon zest and chopped parsley over top, and finish with a pinch of flaky sea salt. Serve hot or warm.