Cast iron skillet.
Skirt steak. 4-5 minutes a side on medium high in a lightly oiled pan (you salted and peppered both sides of the steak, right?).
Half a white onion, 5-6 creminis, both sliced (thin for the onions so they carmelize and 'melt' relatively quickly, thick for the mushrooms so they have a bite to them). Throw in the skillet after you pull the steak out to rest (you let it rest...ALWAYS.). You might need to add a dash of oil.
Start toasting your bread here. I had a Rosemary Focaccia. You might have a hot dog bun. It's still bread. You should still toast it.
Slice some baby swiss from South Mountain Creamery. It's really good. You can find it at The 32nd Street Market (Waverly)
Get some mixed field greens from your CSA. Mine's Homestead Farms in Millington, MD. What? You don't do CSA? Okay, then from your farmers' market. Still? Okay, grab some lettuce. Your favorite kind. I think something like butter lettuce would be good here.
And I'm not harping on the CSAs and markets because of some social crusade (at least not in THIS post). No, lettuces are SUPER in season right now. My first CSA box was spring mix (shown below), mizuna (forthcoming post on damn good pasta), vitamin greens (forthcoming post on damn good omelet), and mustard greens (first casualty of the CSA season). Go get your lettuce from someone that picked it that morning at this time of year because it tastes better. Seriously. Compare. It's lettuce that tastes good. On its own.
And we're back...The bread adds the crunch, so ice berg is not the texture you want. Romaine hearts would get to crunchy too. This sandwich is LARGE. You want a green, if at all, that adds a bright flavor and that sits well on a mound of steak, cheese, and onions/mushrooms.
Go like this from bottom to top.
Onions and Mushrooms hot from the pan to melt the cheese.
Got that? It's a sandwich.
Go make one.