There's a Mexican place in London called Wahaca making decent tacos. We get them with grilled steak, pickled onions, cilantro, and a bit of salsa snug up in a warm, small tortilla. When it came time to rustle together a weeknight dinner for two, I wanted to knock off the Wahaca original.
Start with the onion, which we're going to quick-pickle. It's a cool trick. Thinly slice the onion and then put it in a bowl with a pinch of salt and some vinegar. Stir it all up and let it sit while you prepare the rest of the taco ingredients, and in 15 minutes, voilà, you have quick-pickled onions. A bit mellow, a bit snappy, definitely the perfect counterpoint to the rich beef.
For the meat, I go all out with filet mignon. Sure it's pricier than other cuts, but when slicing the steak, a little goes a long way. And it's just so tender. Crust the steak on the outside with cumin and chili powder. But you can get creative or use whatever you have on hand: chipotle powder, blends, whatever. Then give it a quick sear and slice.
All that's left to do is warm some tortillas (good corn ones!), tear up some cilantro, and crumble some queso fresco (feta would be a good substitute if you need one). You can also pick up some fresh pico di gallo at the supermarket (or make some) if you want to add another layer to these tacos. Then, just pile them high!
Spiced, sliced filet mignon, rare in the middle. The pickled onions, full of attitude. The fresh cilantro. The salty, crumbly cheese. I could eat a dozen.