It's been confirmed it's a cooking gesture. Feigen, Bull, etc, one of those guys said it meant he was cooking defenders. I can't remember who tweeted it, but I know I saw it.
In the 4th quarter of the Nugget game coming back from a commercial at about the 6:45 mark, Bill and Bull show a Harden step back highlight. He does his celebration and Bull says, "I'm getting hungry what are we having for dinner? Let's ask James what he's cooking." And Bill just says "Uh-oh". Then there is silence for like 5 seconds.. Lmao, I thought it was funny.