1. Make the sauce: In a small heavy-bottomed saucepan, whisk together all the sauce ingredients. Heat over medium heat and cook, stirring frequently, until reduced and thickened, about 15 minutes. Keep warm until ready to use.

2. Make the cauliflower: Preheat oven to 400 degrees. Spray a baking sheet with nonstick cooking spray; set aside.

3. Place cauliflower stem side up on a cutting board. Using a sharp knife, cut two or three 1/4- to 1/2-inch-thick slices vertically through the stem portion of each cauliflower. Slices should resemble trees. Use remaining cauliflower for another use.

4. In a small bowl, whisk together egg white with a few drops water until just foamy. Brush cauliflower slices with egg mixture and sprinkle both sides with salt and garam masala. Place cauliflower on prepared baking sheets and transfer to oven; roast until bottom is nicely browned, 10 to 15 minutes.

5. Using a wide, sharp-edged spatula, carefully turn cauliflower. Return to oven and cook until fork tender, about 5 minutes more.

6. Spoon 2 tablespoons sauce onto each of 4 serving plates; top each with 1 slice cauliflower (you may have cauliflower left over) and garnish with pomegranate seeds. Serve immediately.