u/7minegg

I'm grinding a chuck roast for a craft burger. After trimming, the cut looks a little lean, like 10% fat 90% lean. I usually have some extra fat to grind into the meat, but not this time. What can I add to bring up the fat percentage so that the burger is not too lean and dry after cooking? I have butter and a cup of solid duck fat, what can I do with them? Thank you.