I love these things and I find they taste even better using red potatoes, although any will do.
Basically, just take potatoes that are about salt potato size, or a bit larger. Leaving skin on but removing any eyes, cook up about 2/3 of the way. This may be done stove top, microwave or in oven. When I'm in a hurry, I use the microwave.
When cooked, cut in half, then smash down each half. (A sealed can of tuna or cat food works well for this..). Place on cookie sheet, sprinkle with sea salt and vinegar. I prefer cider or malt, but you can also use white.
Place back in oven at 350, until cooked through and crispy on top. Add additional salt and vinegar to taste before serving, then serve immediately.
NOTE: If potatoes are done but still not crisp, you can put under the broiler, but watch carefully! The potatoes may also be finished in a toaster oven, which will allow for a little more crispness.