Try this with cauliflower "steak" slices. Recipe and video, Bon Appetit. August is cauliflower season though available all the time. Meaty, caramelized cauliflower florets and some just-this-side-of-burnt onions all tossed with grated Parmigiano.
Insanely delicious recipe for 5 ingredient, gluten free caramelized onion and rosemary chicken which takes 30 minutes and only one pan, so minimal cleanup required. - using no oil and butter makes it a low syn dinner