Crispy Roasted Potatoes With Cornstarch Crust | CookOS

Crispy Roasted Potatoes With Cornstarch Crust

Name: Crispy Roasted Potatoes With Cornstarch Crust
Prep time: 10 min
Cook time: 35 min
Total time: 45 min
Yield: 4 servings
Cuisine: American
Ingredients: 1.5 lbs baby potatoes, halved; 2 tbsp cornstarch; 1/2 cup water; cooking spray; 2 tbsp vegetable oil; 1 tsp fresh rosemary, chopped; 2 cloves garlic, minced; salt, to taste; black pepper, to taste

These crispy roasted potatoes achieve an extra-crunchy, glassy exterior and tender interior by coating halved baby potatoes in a microwave-gelatinized cornstarch slurry before roasting. The technique delivers restaurant-quality texture consistently.

🌍American 🏷️Roasted potatoes 🏷️Crispy potatoes 🏷️Potato recipe 🏷️Side dish Comfort food

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Total

45 min

Servings

Difficulty

Easy

Est. Cost

$19–$31

Recipe Source

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Ingredients

1.5 lbs baby potatoes, halved
2 tbsp cornstarch
1/2 cup water
cooking spray
2 tbsp vegetable oil
1 tsp fresh rosemary, choppedoptional
2 cloves garlic, mincedoptional
salt, to taste
black pepper, to taste

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Instructions

1
Preheat your oven to 425°F (220°C).
2
In a large, microwave-safe glass bowl, whisk together the cornstarch and water to create a slurry.
3
Microwave the slurry in 20-second increments, whisking between each interval, until it thickens into a jelly-like, pudding texture.
4
Add the halved potatoes to the bowl with the cornstarch mixture and toss thoroughly to ensure they are all evenly coated.
5
Prepare a baking sheet by spraying it with cooking spray, then pouring the vegetable oil on top. Tilt the pan to spread the oil evenly.
6
Arrange the coated potatoes on the baking sheet, cut-side down, in a single layer.
7
Tent the baking sheet with aluminum foil and bake for 15 minutes. This will steam the potatoes and make them fluffy inside.
8
Remove the foil and return the potatoes to the oven. Roast for another 15-20 minutes, or until the bottoms are golden brown and crispy.
9
Remove the potatoes from the oven. Sprinkle with chopped rosemary, minced garlic, salt, and pepper, and toss to combine.
10
Return the seasoned potatoes to the oven and roast for 5 more minutes to toast the garlic and rosemary.
11
Transfer to a platter and serve immediately.

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Tips & Notes

Pro tips

Microwave the cornstarch slurry just until it turns translucent and glossy — this indicates the starch has gelatinized. Under-microwaving results in a thin, non-crispy coating.
Toss potatoes immediately after removing from the oven while the coating is still hot and setting; this helps the glassy finish set firmly.
Spread potatoes in a single layer on the baking sheet and avoid crowding — overlapping pieces steam instead of crisping.
Pat halved potatoes dry before coating to ensure the slurry adheres properly and the exterior crisps evenly.

Substitutions

vegetable oil → olive oil or avocado oil (note: olive oil may brown faster; watch heat)
fresh rosemary → dried thyme, dried oregano, or Italian seasoning (note: use 1/2 tsp dried; more intense than fresh)

Storage & make-ahead

Store cooled roasted potatoes in an airtight container in the refrigerator for up to 3 days; reheat in a 400°F oven for 5–7 minutes to restore crispness.

Equipment

microwave · baking sheet

Common Questions

Why use cornstarch for roasting potatoes?

Cornstarch gelatinizes when microwaved with water, creating a batter that adheres to the potato surface and fries up to a glassy, extra-crispy crust during roasting.

Can I use regular potatoes instead of baby potatoes?

Yes, but cut them into similar 1.5-inch pieces so they roast evenly and the cornstarch coating crisps uniformly.

How long do these potatoes stay crispy?

Best served immediately after roasting. Leftovers can be reheated in a 400°F oven for 5–7 minutes to restore crispness.

What if I don't have fresh rosemary?

Dried rosemary (1/2 tsp), thyme, or Italian seasoning work well. Adjust to taste since dried herbs are more concentrated.

Can I make the cornstarch slurry ahead of time?

Yes, prepare the slurry up to 2 hours ahead and refrigerate. Microwave it again for 30–45 seconds before coating the potatoes to ensure it's warm and coats evenly.