Rosti: Crispy Potato Pancake with Mushrooms and Onions
What do you get when you have a cake with a creamy and delicate interior protected by a crispy caramelized exterior? You have a rösti. A potato pancake like no other. Its’ soft creamy interior holds together with just the right amount of the potato’s natural starches, creating a pancake that is tender, creamy and crunchy. Rösti originated in Switzerland and was a breakfast staple for farmers. Now, people from all over the world enjoy these potato cakes.
I have enjoyed rosti in restaurants and wanted to see if I could recreate them for myself. After researching many recipes, I decided to use a recipe from The Food Lab by J. Kenji Lopez-Alt. His science based technique is typically spot on, inventive, and not too difficult to follow. After making his recipe a few times I picked up a few skills and some new information.
Like life in general, the key to making a successful rösti is all about balance. They are like fritters or latkes, but are thicker and creamier. The type of potato and the technique used to prepare them, work together and create the perfect amount of starch necessary to hold the whole pancake together. Too little starch and the rösti falls apart when you cook it. Too much starch and you have a sticky pancake. Have you ever played with potato starch mixed with water? Its gooey stuff and not something you want in your pancakes.
Kenji believes Russet potatoes are the best ones to use. They are high in starch and will create pancakes with fluffy interiors and crunchy outsides, like the perfect French fries. I agree with him if you follow his technique. For experimentation, I tried a different parcooking method using Russet potatoes and the results were not so great.
Rösti has essentially one ingredient and the key to keeping them intact is the initial preparation. Good sharp tools, like a mandoline or a very sharp knife will cause less potato starch from releasing. A box grater is not as sharp but does a good job cutting the potatoes into the right size.
Parcooking helps prevent the potatoes from oxidizing and give the rösti the right texture. He likes to parcook the potatoes in a microwave which is easy enough, and eliminates a step common in other recipes. I often read potatoes are grated raw, then squeezed to rid them of excess water before assembling. Parcooking potatoes gives the potato cake great texture and fully cooked potatoes throughout the pancake.
Unfortunately, my potatoes oxidized even though I sliced them with a mandoline and parcooked them in a microwave. I am not sure why, but one theory I have is my potatoes where doing what potatoes do, oxidize when exposed to air. Maybe I did not work fast enough, or my knock off Japanese mandoline needs sharpening. After several trials, I am still working this out.
To experiment, I parcooked the potatoes whole in a microwave, let them cool, then grated them using a box grater. This produced rosti with a light and creamy color, but looked and tasted like mashed potato cakes, not a rosti. Maybe a medium starch potato like, Yukon gold is better suited with this technique. Oh, so many variables to figure out, and so little time.
If you have a non-stick pan, it will be a lot easier to make. I do not own one and used a cast iron skillet. They are good pans to use just harder to maneuver the rösti out of the skillet. The sides of my pan are more vertical than they are slopped. My rösti had to slither up and over a cast iron mountainside before it could ease on to a plate. It required some extra encouragement with my spatula to get the rosti to “slide” out of the pan.
As I cooked rösti, I was reminded of making a traditional Spanish tortilla. The amount of oil and the heat of the pan had to be just right so the tortilla would cook properly and slide in and out of two different skillets multiple times. Rösti has less ingredients than a Spanish tortilla, which makes the delicate balance all that more important. It is not hard to make rösti, just more particular.
Traditionally, rösti is considered a side dish, but I love to serve rösti as a meal topped with an egg and salsa. They are also delicious served with any vegetables like spinach. I used Kenji’s suggestion and mixed in a layer of mushrooms and onions because they are one of my favorite foods. I really like this idea and will make it a staple feature whenever I make them.
Serve rösti as an appetizer with garlic or saffron aioli. It is a delicious small plate option for any cocktail party. Add smoked or cured fish, pickles, eggs, vegetables, aioli, and your guests have a satisfying and unexpected meal.
I would love to hear from you about your experience making rösti. Let me know in the comments section below the recipe how you like to prepare rösti. Enjoy!
Rösti: Potato Cake with Mushrooms and Onions
- 3 medium russet potatoes l lb- 1.5 lbs /680 g rinsed peeled and cut with a box grater or mandolin
- 5 Tb/ 62 g olive oil divided
- 1 medium onion
- 4 oz / 125 g mushrooms thinly sliced
- 2 garlic cloves minced
- 1 tsp fresh thyme or 1/2 tsp dried thyme
- Kosher salt and ground black pepper
Place the prepared potatoes in a microwave dish and cook on high for around 5 minutes. You do not want the potatoes overcooked and mushy, they should still have a slight bite in the center.
While the potatoes are cooking, heat 1 Tb olive oil in a heavy 10-inch skillet and add the onion and mushrooms. Cook the mushrooms and onions until soft and translucent and just beginning to brown, around 6 - 8 minutes. Add the minced garlic, thyme and a pinch of salt and pepper, stir to mix and cook until you begin to smell the garlic's perfume. Remove the mushrooms and onion from the pan and set aside.
Wipe the skillet clean and return it to the burner. Turn the heat to medium and add 2 Tbs to the skillet. Heat the oil until shimmering. Make sure there is an even coating of oil across the whole pan, then spoon half of the potatoes into the skillet. Press down on the potatoes with a rubber spatula and form the potatoes into a pancake. Season lightly with salt and pepper, then spread the mushrooms and onions over the potatoes. Add the remaining potatoes to cover the mushrooms and onions, then press down on the potatoes to cover the top of the pancake.
Cook the rösti on one side for around 7 minutes. Do not disturb the pancake for at least 4 minutes into the cooking time. After 7- 8 minutes, run a thin spatula around the edges and underneath the potatoes to loosen it from the bottom.
Slide the potatoes onto a plate large enough to hold the rösti. Place another plate, upside down, on top of the plate holding the rosti, so the rims are kissing each other. Flip the plates over, so the bottom plate is now the top and lift off the plate. You should see a beautiful golden brown crusty rösti.
Wipe off any stuck bits from the bottom of the pan and add 2 Tbs olive oil.
When the oil is shimmering, slide the rösti back into the skillet and sprinkle with salt and ground pepper. Cook for 7 more minutes.
When finished, loosen the rosti from the pan and slide it onto a serving plate.
Keep warm or serve immediately.
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