We're going to need to get a marinade/rub on this, so throw parsley, onion, mint, roasted garlic*, cumin, allspice, cumin, paprika, ras al hanout, urfa pepper, and Aleppo pepper into a food processor.
(A bit of salt wouldn't hurt, either.)
Blend that up into a thick paste, and smear it over the riblets.
While that's sitting there, getting more delicious, thickly slice the cauliflower. You're looking for "steaks", although you only really get two that properly hold together. The florets should be of equal thickness, somewhat.
Meet the grill.
Cauliflower first. Steaks can take raw grill marks, but the florets had to go to a grill pan, which has large holes in the bottom to let the raw heat hit the veggies. Get those things cooked, slightly charred, and softened.
When the cauliflower is mostly done, we should get the riblets going. Medium high heat, and right on the grill.
Cook them until brown, crispy, and the fat starts rendering and threatening substantial grill immolation.
The cauliflower should also be slightly charred, and warmed through and soft.
Plate, with some pesto dotted on the cauliflower for color and an herbal lift.
*Roasted garlic = 1 head garlic + 400 degree oven + 1 hour.
