Here, one might exploit the reaction p(p,pi+)d (or, rather, it's antimatter equivalent, which makes a negative pion), at a center of mass energy above threshold for creating the charged pion (which has a mass of 139.579 MeV. This is wildly energy negative, but if one has already invested many GeV in making each antiproton that's presumably acceptable. The cross section for this reaction is only ~200 microbarns, but that will be many orders of magnitude higher than the ordinary fusion cross section.
The solid antimatter one would probably target as an end goal would be anti-(lithium hydride).