Concordia: Salsa
Buy this firstRanked the best all-round Concordia expansion by The Dice Drop, and the most-recommended pick in BGG buy-order threads; salt and two strong maps in one box.
Needs: Just the base game
Adds: Salt as a wild resource, Forum tiles that give each player special powers, and two new maps (Byzantium and Hispania).
Fixes: Gives the vine resource a real use (salt cities) and makes awkward storehouse turns more forgiving, so mistakes hurt less.