Start by preparing the cowboy butter. In a bowl, combine the softened butter, parsley, chives, garlic, smoked paprika, Worcestershire sauce, and cayenne pepper. Mix until well combined. Transfer to a piece of plastic wrap, shape into a log, and refrigerate for at least 30 minutes to firm up.

Season the flank steak with salt and black pepper on both sides. Heat the olive oil in a skillet over medium-high heat. Once hot, add the steak and sear for about 4-5 minutes on each side for medium-rare, or until desired doneness.

Remove the steak from the skillet and let it rest for 5-10 minutes before slicing it thinly against the grain.

While the steak is resting, slice the slider buns in half. Toast them lightly on the skillet or in a toaster if desired.

Assemble the sliders by spreading a generous amount of cowboy butter on the bottom half of each bun. Layer with sliced steak, shredded lettuce, and tomato slices. Top with the other half of the bun.

Serve immediately and enjoy!