Stone Soup is an ongoing quarantine feature in which I come up with a recipe that uses the impossible thing in your cupboard, without making you go to the store or wasting any of your ingredients. Last time, we made bisque.

Liz says:

So my mom is a terrific gardener and had some purple Japanese sweet potatoes (this is what she called them) take over one of her planting boxes and she gave us a couple of the tubers earlier this year (pre Coronavirus). My first attempt at cooking them was by oven roasting with some salt pepper and herbs, which tasted okay but was super soft and crumbly. I chopped up the rest and froze it not knowing what to do with it.

Now since I have some free time and a small child who is entertained by being my sous chef, I have been trying to figure out something better to do with my weird frozen sweet potato chunks. The tuber was pale skinned, the insides are streaked with purple, and it turns entirely purple when cooked. it definitely isn’t taro in flavor, It’s very sweet and goes to fluffy mashed potato texture really easily. It doesn’t look like quite the right color for ube.

Based on the description, it sounds to me like Liz is describing an Okinawan sweet potato. This kind of purple sweet potato is, per its name, native to Okinawa, and it’s popular in Hawaii.

Let’s make a few distinctions before we dive in. As you may recall from our adventures in sweet potato soup, Americans tend to get confused about the distinctions between yams and sweet potatoes. Fortunately, purple tubers tell you the truth with their names. Ube is also known as the purple yam; it’s from the family Dioscoreaceae, where true yams live. The Okinawan sweet potato, meanwhile, is an actual sweet potato: it belongs to the family Convolvulaceae, where all sweet potatoes hang out as the tuberous roots of certain strains of morning glory flowers.

All that’s to say: Liz is right to say that the purple sweet potato ain’t ube! It’s a whole other thing. In contrast to other types of purple sweet potato — like the Stokes or the Murasaki — the Okinawan sweet potato is relatively dry and starchy, which doesn’t make it the ideal candidate for baking into pies or roasting.

But you know what it’s fucking perfect for?

Hashpurples

See, because… because they’re purple. And not… not brown. I don’t think this holds up, but I’m going to stick with it.

When you’re making a hashbrown, you want a good dry potato with enough starch to stick together and crisp up. I think that makes the Okinawan sweet potato an ideal candidate! You can also apply the method I’m about to outline to orange-fleshed sweet potatoes and unsweet potatoes like russets. Wow, it sure feels awkward to try to describe the distinctions between types of potatoes! Good thing that part of the recipe’s over.

Step One: Wash ‘em. We’re keeping the skins on for this recipe, which I do for pretty much every potato recipe. This is a thoughtful, intentional strategy that I employ to maximize the nutrients in the recipe. It’s definitely not just because I don’t feel like peeling shit.

If you want to be thorough, soak your sweet potatoes in cold water for about an hour, and then give them a good hearty scrubbing with a brush or a rough cloth. If you want to be me, hold them under a running tap and rub off the loose debris with your hands, then say “that’s probably good enough” because they’re going to get washed again later anyway. Up to you.

Step Two: Shred ‘em. This is a good spot for Liz to employ her small child as a sous chef, because it’s labor-intensive and one of the best parts of getting children to help in the kitchen is handing off the grunt work. I like to use a box grater on top of a cutting board best for this, because it captures the potato shreds. Shred as much potato as you feel like cooking, using the medium holes with the the cutting edge on the bottom.

If you’re having a child do this work, you might want to slice the sweet potatoes into quarters to fit into littler hands. Put a dishtowel under the cutting board to catch stray shreds and potato… juice? Ugh. The liquid runoff from this process is definitely potato juice, but that’s not a set of words I ever wanted to put together.

Step Three: So much rinsing. When you make hashbrowns, you want them crispy, right? This is crucial. That means you need to knock excess starch and liquid off your potatoes.

To accomplish this, fill up a big bowl with water and dump in the shreds. Give it a stir with your hands, then drain into a strainer or colander. Repeat this process three times. The water you pour off should get gradually more clear, but don’t worry if it’s not completely clear by the third rinse. Then, press the potato shreds between paper towels to get as much excess liquid off as possible.

You can also use a salad spinner to make this process a lot faster, easier, and less messy. Just put your potato shreds into the basket and fill the spinner up halfway with water. Give it a spin to agitate, then lift out the basket, dump the water out of the bowl, and repeat three times. Finally, spin your potatoes to dry them as thoroughly as possible (I usually do three rounds here, too).

Step Four: Seasoning. I like to season my hashbrowns in the instant before they go into the pan. Don’t season them way ahead of time, because potatoes and salt have a complicated relationship and you’ll wind up with a soggy mess on your hands. My preference for seasoning here is not going to surprise anyone: salt, black pepper, onion powder, garlic powder, paprika, thyme. Be generous, but don’t go overboard on the salt — you can always add more later. Toss thoroughly to distribute your seasonings as evenly as you can.

Step Five: Pan time. This is the part where small helpers should be at a distance. Put a big shallow pan over high heat. Add a decent amount of oil and let it get hot before you add your shredded, seasoned potatoes to the pan. They should overlap, but not be in too thick of a layer.

Now don’t fucking touch ‘em. I know you want to stir that pan, but the most important thing you can do to get yourself some crispy-ass hashbrowns is leave them alone. You can gently lift them at the edges with a spatula to check the color of the underside, but that’s it. I mean it.

If you’re working with lighter-colored potatoes, cook them until they’re golden-brown on one side, and then flip them. If you’re working with darker-colored potatoes, cook them until they look crispy on the bottom, and then flip them. Add a little more oil to the pan, and then let them sit until both sides look friendly.

That’s it! You did it! You have hashbrowns! This is the simplest version of them. You can also add sauteed vegetables like onions and bell peppers, if you want. You can season any which way. Serve an over-medium egg on top with a drizzle of sweet soy sauce, or your favorite hot sauce, or nothing at all if you’re a breakfast minimalist. Sweet potatoes make good friends with barbecue sauce, or with maple syrup and breakfast sausage. Don’t let your dreams be dreams, etc.

Just the recipe:

Hashpurples

• Thoroughly wash the outsides of several Okinawan sweet potatoes.
• Shred using the medium-shred size of a box grater.
• Drop potato shreds into a big bowl of water, swirl them around to remove excess starch, and drain. Repeat x3.
• Pat dry with paper towels, or thoroughly spin dry in a salad spinner.
• Season with salt, pepper, onion powder, garlic powder, paprika, & thyme.
• Heat oil in a large, shallow skillet over high heat.
• Once oil is shimmering, add potato shreds to the pan in a single even layer. Do not stir.
• Once potato shreds are crispy on the bottom, flip once. When they’re crispy on both sides, congratulations! They’re hashbrowns.