Ingredients

1/2 cup olive oil
1/4 cup red wine vinegar
2 rosemary branches, leaves chopped
2 garlic cloves, minced
1/2 teaspoon crushed red pepper flakes
1 1/2 teaspoons kosher salt
3 pounds sirloin tips, in thin strips or 1 1/2-inch cubes
1/2 teaspoon freshly ground black pepper

Directions

Mix together olive oil, vinegar, rosemary leaves, garlic, red pepper flakes and 1/2 teaspoon of the salt in a non-reactive 3-to 4-quart bowl. Immerse the beef in the marinade. Refrigerate 4 hours to overnight.

To cook, remove as much marinade as possible from the beef. Thread the beef on skewers, or on sturdy sprigs of rosemary. Sprinkle all sides with the remaining teaspoon of salt and the pepper. Grill over medium-high heat, turning every 1 1/2 minutes, until beef is deeply browned on the outside and still rare on the inside, 8-10 minutes (or to personal preference).