Peel the potatoes, cutting any larger ones so they’re uniformly sized. I cut mine to be a little smaller than a ping-pong ball.
Wash the potatoes in cold water to remove any extra starch then add them to a large empty pot. Boil water enough water to cover the potatoes well (about 2 inches higher than the potatoes) pour over the potatoes, salt the water, and parboil for 5-7 minutes, then drain in a strainer and leave dry.
Once dry, gently shake the strainer to rough up.
Add the potatoes into a large bowl. Add the oil, salt an pepper, gently stir to coat and transfer to a baking sheet in one layer, and add the fresh thyme.
Roast in the hot oven for 40 to 45 minutes, or until crispy and golden brown.
Transfer to a plate lined with paper towels to drain off any excess oil and serve.
Soak the cut potatoes in salted ice water for 20 minutes before starting. The salt adds flavor and soaking removes excess starch that can cause them to stick to the pan and creates a much crisper finish.
To safely add the potatoes to the boiling water, add the potatoes to the empty pot, boil the water in a kettle and then pour over the potatoes. This keeps you from having to drop them into the hot water and getting burned by the splash.
To tell if the potatoes are parboiled enough, insert a fork into a potato. They are done if the fork slides in fairly easily, but meets some resistance in the center.
Don't overcrowd the potatoes on the pan. Overcrowding will cause heat from the pan to get trapped under the potatoes and cause them to steam instead of roast.
For extra crispy potatoes, turn them in the pan halfway through the cooking time.