Chimichurri Sauce: In mini food processor, pulse parsley, basil, oil, vinegar, lemon juice, garlic, salt, pepper and red chili flakes until smooth.
Skewers: In large pot of boiling salted water, cook potatoes for 12 to 15 minutes or until tender. Drain and let cool slightly. Cut into 1/2-inch pieces. Thread potatoes and steak evenly onto 4 metal, bamboo or wooden skewers. (If using bamboo or wooden skewers, soak skewers in cold water for at least 1 hour before using). Brush with olive oil and season with salt and pepper.
Preheat grill to medium heat; grease grate well. Grill skewers, turning occasionally, for 6 to 8 minutes for medium-rate or until desired doneness and potatoes are grill-marked.
Serve skewers wit Chimichurri Sauce for dipping.
Tip: Substitute trip loin or rib-eye steak for sirloin if desired.
Tip: Thread chinks of red onion or 1-inch pieces of green onion onto skewers along with potatoes and steak if desired.