Cook potatoes in microwave oven about 8 minutes on high. Let stand to handle, 5 minutes. Coarsely chop the potatoes.
Heat the extra-virgin olive oil and butter in a nonstick skillet over medium-high heat. When hot, add potatoes to the skillet. Grate the onions over the skillet with a hand held grater on the large side. Toss the potatoes and onions to coat evenly in hot fat and season with grill seasoning. Brown and crisp the potatoes and onions 6 to 7 minutes. Serve hot alongside chicken and egg sammies.