"Si no tienes las cebollas, olvidate!" If you don't have the onions, feghetaboutit!
I wish I could tell you that that was a quaint saying my abuelita used to tell me, but sadly, it's not. It just came to me as I was frying up my steak for dinner this evening. And it's really quite true-- if you toss the onion, garlic, citrus marinade, or mojo, you're missing the best part!!