Cooking “purple sweet potatoes” or “purple yams”

Question

I recently bought something that was labelled at the grocery store as a "purple sweet potato". They were larger than what I am used to for sweet potatoes, but looked similar, although they had a purple skin on the outside and white flesh on the inside. I figured since they were labelled as "sweet potatoes", I would prepare them the same way I like to prepare regular sweet potatoes, by boiling them first (for about 40 minutes), then removing the skin, slicing it into wedges and then pan frying them. I have done this many times with normal sweet potatoes, and it works quite well.

However, after I boiled the purple sweet potatoes for 45 minutes, I pulled them out to take the skins off, and they were soft and stringy and incredibly off putting - they felt the same way as a gummy mashed potato would feel, and they fell apart all over the place.

Are they more like a potato, requiring less boiling time? Or is there something else going on here that I am missing?

Edit: I went to the grocery store today, and they are now labelled as "purple yams". I don't know if that makes a difference or not. I also got a picture of them, to make my description a bit clearer.

Answer 1

I used to cook plenty of purple sweet potatoes when I was living in africa:) Sounds like you maybe cooked them too long...

They can be extremely tasty, sweet with a "perfumy" hint if you are lucky. They are best boiled with the skin on like you did and peeled afterwards (as the taste is preserved better that way). As for cooking time it really depends on the size (which means the potatoes are likely done at different times) but you can always feel when they are done by pressing on the potato with a fork - it should give slightly/be soft. I think it usually took me about 30min but I didn't use a clock. It may shorten the cooking time slightly to make holes in the potatoes with a fork (this also adds to the "creaminess").

I guess they do sometimes get a softer, more "creamy" consistency than your usual potato when well done. However the taste is richer and in my opinion far superior to orange sweet potato. If you prefer a firmer potato, just let your potatoes stay on the firm side (in my experience, though, the taste is enhanced by letting them go soft). But boiled ones would anyways mainly be for puddings as it gets rather sweet.

For panfrying I would suggest avoiding boiling the sweet pots first. Simply peel/wedge them raw, fry them as chips until done and serve with a spicy/hot dip - yum.

Answer 2

These look a lot like some varieties of Japanese and Korean sweet potatoes, which often have purple skin and white flesh. I've found that they are drier and maybe starchier than orange sweet potatoes. They are hard to roast as they tend to dry out, but steaming or simmering in water work well, as does frying. If you search around for Japanese or Korean sweet potato recipes, I bet most of what you find will work well for these.

Answer 3

Since sweet potatoes are usually classified by the color of the interior flesh, most parts of the world would call these white sweet potatoes. I think the easiest way to use these is to bake or to slice into half-inch thick circles, steam or boil about 20 min. After the initial cooking, you can also puree them with egg and coconut milk then bake similar to pumpkin pie, with or without extra elements such as crust, sweetener, spices.

I cook a lot of sweet potatoes - with flesh inside that is white, orange (sometimes called yams in US) and purple (Okinawan). I have noticed some variation in their handling.

Baking (in skin) 40 min @350F:

• Orange are highest moisture and can be a little stringy, develop to a very soft consistency like cooked pumpkin.
• White are somewhat like regular baked potato in texture.
• Baking purple sweet potatoes tends to make them dry and starchy, hard to eat without adding liquid.

Steaming/boiling (peeled or not, cut into pieces) ~20 min:

• Have not tried with orange sweet potatoes.
• White and purple seem more starchy and can crumble/disintegrate if overcooked

Microwave: I have heard 5-8 min on high, and of course it depends on the machine, but I always seem to get undercooked spots. For me it works best with long narrow orange sweet potatoes, but not my preferred method.

Answer 4

The purple sweet potato according to materials I've researched had white flesh did you say? Well all white fleshed potatoes sweet or not are faster to cook usually about fifteen to thirty min.

Answer 5

When my wife first saw one of these, she cooked it like a regular sweet potato or yam, about 45 minutes or an hour in the oven at 350. It was as hard as a rock, so I figured we cooked it too long. The next time I bought one however, it had instructions stuck to it on the barcode label. As it turns out, you have to cook these much longer than a yam, 2 hours, plus you have to coat them in olive oil first and wrap them in foil....it may be a pain, but well worth it! One of the tastiest things I have ever eaten.

Answer 6

I bought these purple yams by mistake and didnt know what to do with them. So I peeled them sliced them very thin, and placed them on a baking sheet. I drizzled olive oil, salt and pepper and roasted these for 20-25 minutes at 400 degrees. They were very good and tasted great.