• 1 Tbsp. kosher salt
• 1 tsp. dried lavender or herbes de Provence
• 2 Tbsp. ground coffee
• 1 Tbsp. sweet paprika
• 1 1/2 tsp. smoked paprika
• 1 piece (about 2 1/2 pounds) trimmed, boneless beef top round

• 2 Tbsp. olive oil
• 1 large white onion , thinly sliced
• 1 red bell pepper , stemmed, cored, and thinly sliced
• 1 yellow bell pepper , stemmed, cored, and thinly sliced
• 1 tsp. kosher salt
• 1/4 tsp. freshly ground black pepper
• 4 Tbsp. (1/2 stick) butter , divided
• 6 hoagie rolls , split
• 6 slices Provolone cheese
• 2 cups shredded iceberg lettuce (optional)

To make roast beef: Preheat oven to 350°. Pulse salt and lavender together in a spice grinder or blender until finely ground; transfer to a medium bowl. Alternatively, crush the lavender together with the salt in a small bowl using your fingers or the back of a spoon. Add in coffee and both paprikas.

Rub coffee mixture over entire surface of top round, then arrange on a rack in a roasting pan and roast until a meat thermometer inserted in the thickest part of the beef registers 125°, about 1 hour. Let cool 1 hour, then cover and chill until completely cold, 4 hours. Slice against the grain as thinly as possible.

To make sandwiches: Heat oil in a large skillet over medium heat. Add onion and peppers and cook, stirring occasionally, until softened and just caramelized, about 15 minutes; add salt and pepper. Meanwhile, working in batches, melt about 1 teaspoon butter per roll in a large skillet over medium-high heat. Brown cut sides of rolls until toasted and golden, 1 to 2 minutes; transfer to a plate. Repeat with rest of butter and rolls.

Return skillet to heat and melt remaining 2 tablespoons butter. Working in 2 batches, add sliced beef and cook, tossing occasionally, until browned, 3 to 4 minutes. Return all beef to skillet. Scatter onion and peppers over beef, then top with cheese and cook, without stirring, until cheese melts, 2 to 3 minutes more. Transfer beef mixture to rolls and top with lettuce, if using.