Pressed Steak and Horseradish Sandwich

We're having a couple of 90º days up here in Minnesota. And to make matters worse, the humidity is at 74% and the dew point is not too far behind that. So the last thing I want to do is go grilling on the deck at 5:30pm when the weather is at it's most extreme.

This nifty little recipe from Food Network Kitchen let's me avoid that. You can do your grilling in the cooler part of the day because this is a pressed sandwich. Grill it, then press it in the fridge for 3 hours by setting a cast iron pan or foil-wrapped brick on top of the sandwich.  This serves eight normal humans or four linebackers.

Ingredients
1 flank steak (about 1 1/2 pounds)
2 tablespoons Worcestershire sauce
2 tablespoons extra-virgin olive oil
Kosher salt and freshly ground black pepper
1/2 cup mayonnaise
2 tablespoons prepared horseradish, drained
2 tablespoons whole-grain mustard
1 medium to large red onion, sliced into 1/4 inch rounds
1 large loaf rye bread (unsliced)
4 cups baby arugula
1 large tomato, thinly sliced

Directions

1. Prepare your grill for direct cooking over high heat.
2. Place the flank steak in a casserole dish or baking pan. Drizzle with the Worcestershire sauce, 1 tablespoon olive oil, 1/2 teaspoon salt and a few grinds of black pepper. Rub this mixture all over both sides of the flank steak and let sit at room temperature for 30 minutes.
3. Mix together the mayonnaise, horseradish and whole-grain mustard in a small bowl. Set aside.
4. When the grill is hot, cook the flank steak for 6 minutes on each side. When done, remove steak to a cutting board, tent with foil and let it rest 10 minutes before slicing very thinly across the grain. 
5. Drizzle the onion slices with the remaining tablespoon olive oil and sprinkle with salt and pepper. Grill the onion on both sides to char and soften, about 2 minutes per side. Transfer to a bowl. Check seasoning and add more salt and pepper, if necessary. Cover with plastic wrap to continue softening.
6. Slice the bread loaf in half horizontally and lay the two halves cut-side up. Pull out some of the bread from both halves, leaving a 1/4-inch border (see top photo). Spread the horseradish and mayonnaise mixture on both halves. Layer half of the arugula, then the onion and the steak on the bottom half of the loaf and season with salt and pepper. Add the tomatoes, remaining arugula, more salt and pepper and top half of the loaf. Wrap tightly in parchment, wax paper or plastic wrap and tie with twine if necessary. Press 3 hours with a brick or cast-iron skillet on top to flatten the sandwich, refrigerated. About 45 minutes before serving, bring the sandwich to room temperature. Then slice and serve.

Pairing: It's 90º and it's a sandwich. I'll take a pilsner, please.