Remove leaves from cauliflower. Slice cauliflower, vertically, into 3/4 inch thick slices, making sure that each slice includes the stem.
Combine olive oil, lemon juice and garlic in bowl; mix well. Pour mixture into large resealable plastic freezer bag; add cauliflower. Tightly seal bag. Turn bag several times to coat cauliflower well. Place bag into 13x9-inch pan. Refrigerate, turning occasionally, at least 30 minutes.
Heat gas grill on medium or charcoal grill until coals are ash white.
Remove cauliflower from marinade with slotted spoon; discard marinade. Sprinkle both sides of cauliflower steaks with salt. Place onto grill; close lid. Grill, turning once, 20-25 minutes or until cauliflower is tender. Place 1 slice cheese onto each cauliflower steak during last 2 minutes of grilling.
- When cutting cauliflower, be sure a section of stem is attached to each steak. This will help the cauliflower steak to remain intact when grilling.
- If cauliflower is over-cooking on the outside, but is not yet tender, move cauliflower away from heat and continue cooking with grill cover closed until cauliflower is tender.