Roast Beef with Grilled Red Onions, Radish Slaw, and Black Pepper Mayonnaise

Here’s one for a party: Roast a large piece of beef and feed a big crowd. If your gathering is in the backyard, toss the onions in the marinade and grill them until they’re a little bit charred. But if you are cooking the onions indoors, roast them in a cast-iron skillet until they start to caramelize. The radish slaw—a mix of daikon and red radishes with a little bit of horseradish (a traditional condiment for roast beef)—contributes crunchy, spicy coolness. The mayo, though, is the genius of the sandwich. When you order a roast beef sandwich at a restaurant, you always hope it will come au jus—everyone loves to dip into those delicious flavors. Well, as ’wichcraft sandwiches are often eaten on the go, we let the beef rest after we roast it and then use the drippings in the mayo. You get the flavor of the dip without the drip (although, admittedly, this is still a three- or four-napkin sandwich).