3 tablespoons unsalted butter, softened
3 tablespoons chopped fresh cilantro
1 teaspoon minced garlic
1/3 cup finely grated cotija cheese
1/8 teaspoon cayenne pepper, or to taste
1 tablespoon extra-virgin olive oil
2 russet potatoes, about 9 ounces each, peeled and cut lengthwise into 1/8-inch-thick slices and again into 1/8-inch-wide strips, set aside in a bowl of cold water
2 pieces filet mignon (7 ounces and 1 1/2 inches thick each), room temperature
Coarse salt and freshly ground pepper
1 teaspoon vegetable oil