Trim cauliflower leaves and cut out about 1-1/2 inches of stem, making sure florets stay intact. Rinse and blot dry. Place in the center of a square sheet of foil on a baking sheet.
Combine oil & garlic. Gently warm until fragrant, but do not let garlic turn brown. Strain oil thru fine sieve, pressing on garlic to get all oil. Discard garlic. Stir mustard seeds and pepper into oil.
Spoon warm oil mixture as evenly as possible over cauliflower. Sprinkle evenly with salt. Crimp foil to hug base of cauliflower.
Bake uncovered at 375 degress about 1-1/2 hours or until just tender (test with tip of sharp paring knife.
Can be made a day ahead, refrigerated (wrap air-tight), brought to room temperature, and reheated in microwave.
Place on a platter layered with kale leaves. Sprinkle with fresh parsley or chopped chives. Cut in eight wedges and serve hot, garnished with lemon wedges.