Chris Martin & Gwyneth Paltrow -- Hold The Beef ... We're Burger Buddies

Chris Martin and Gwyneth Paltrow are showing the world their divorce is 100% USDAmicable ... because they spent this past Sunday together chowing down on burgers.

The Coldplay front man and Iron Man's squeeze were snapped out in L.A. together for the first time since their April divorce.

We'd say they buried the hatchet ... but they never had 'em out.