Stout beer is the way to go! If you can find Guinness in cans or bottles to keep this stew Irish, great! If not, other dark beers will work too. A Modelo Negro from Mexico is great, or any brand of porter.  Don’t freak out if you can’t easily find a dark ale. If worse comes to worst, you can even use light beer…you just have to call it “Irish Stew Lite.”