Remove the outer leaves from each cauliflower head. Cut off the bottom stem end so that you create a flat base and can stand the cauliflower up on a cutting board. Resting the cauliflower on the stem, use a large, sharp knife to trim away the sides, then cut the remaining head into 2 or 3 1-inch “steaks,” depending upon the size of your cauliflower. Reserve the sides for another use (see notes). In a small bowl, stir together the olive oil and honey. Brush half of the olive oil mixture over the top of the cauliflower steaks, then sprinkle 1 tablespoon Montreal seasoning over the top.
Prepare the avocado topping: in a medium bowl, whisk together the parsley and cilantro, garlic, jalapeño, lime juice, salt, pepper, oregano, and olive oil. Add the avocado and gently stir to combine. Taste and adjust the seasoning as desired.
Heat a grill to medium (about 350 degrees F). Place the seasoned side of the cauliflower steaks facing down on the hot grill, then brush the tops of the steaks with the remaining olive oil mixture and sprinkle with remaining 1 tablespoon Montreal seasoning.
Cover the grill and let cook for 6-8 minutes, until the bottom begins to char. Flip the cauliflower, then re-cover the grill and cook 5-7 additional minutes, until the cauliflower is tender. If your cauliflower is very thick, you may need to cook a few additional minutes per side. Remove from the grill. Serve hot with the avocado salsa and an extra sprinkle of salt as desired.
TO STORE: Store leftover cauliflower steaks in an airtight container in the refrigerator for up to 4 days.
TO REHEAT: Rewarm leftovers on a baking sheet in the oven at 400 degree F or in the microwave.
Nutrition was calculated using 2.5 total pounds of cauliflower, as some of the florets are cut away.