The secret to crispy oven roasted potatoes is all in the method: a quick parboil, a hot pan, and a generous toss in oil and butter guarantees crisp, golden brown edges and tender centers every time.
Add the potatoes to a medium saucepan, sprinkle with salt and cover with cold water. Bring the water to a full boil, then reduce the heat and simmer for 3 minutes. Drain well and return to the pan for a minute or two to evaporate any excess water.
Combine the melted butter and olive oil on a baking sheet (17 x 11-inch) and tilt it back and forth to coat the surface evenly. If you can't cover the surface completely, add a little more oil. Place the pan in the oven for 5 minutes to preheat the butter-oil mixture.
While the pan is heating, dust the potatoes lightly with flour, tossing to coat as evenly as possible. Add the potatoes to the hot pan and using tongs, turn the pieces to coat them with the butter-oil mix. Spread them in a single layer, allowing for a little space between the pieces for optimal crisping.
Roast until browned and crispy, 45 to 50 minutes, turning the potatoes every 15 minutes to ensure even browning. Season to taste immediately with All-Purpose Seasoning Blend (or salt) and freshly ground pepper and serve.
Notes
For best results, use a combination of melted butter and oil together, as butter alone would burn before the potatoes were cooked through. Choose an oil with a high smoke point like avocado, canola, or safflower. Other options with high smoke points are clarified butter, ghee, and refined duck fat. Any of these could be used in place of the butter/oil combo.