Preheat oven to 425 degrees. Place a sheet of parchment over your biggest sheet pan. If necessary, use two sheet pans. Toss potatoes in the olive oil and salt and arrange them in a single layer on the parchment. Make sure the potatoes have plenty of room between them and their neighbor to ensure good caramelization. Roast for 12 minutes then toss and roast for another 12. (If your oven runs extra hot or your potatoes are diced smaller and it looks like they are browning too fast, just roast for 10 minutes each time.)Add the butter, garlic and herbs and give the potatoes a final toss them roast them for another 5 to 8 minutes. They should be browned and crisp and fork tender.