Preheat oven to 400 degrees fahrenheit.
Rinse green beans and potatoes. Set green beans aside.
Slice potatoes into halves, and then quarters, or more as needed to produce pieces that are no more than ½" thick.
Pour potatoes onto cookie sheet, and drizzle lightly with oil, tossing them to coat, and then season generously with kosher salt, and a little garlic and onion powder.
Bake potatoes on middle rack for 15 minutes, or until they just begin to turn golden brown.
Remove, and add green beans to pan, drizzle with small amount of oil if potatoes have soaked up all the oil, and toss.
Return to oven for an additional 10 minutes, or until green beans darken slightly, and potatoes begin to crisp up a bit more.