Should I par-boil the pickled potatoes before roasting them

In my opinion, it's a matter of how much time you have and what temperature your oven is set on already. I make these a lot, with a variety of dishes, so I've used multiple cooking methods.

Ideal: They roast best, I think, being boiled just for a few minutes then roasted at 475 F for 30 minutes.

Oven's already on low: If I have a more slow-cooking item already in the oven at 350 F, then I'll go ahead and put the potatoes in raw and leave them to roast for 60-90 minutes.

Need them quickly: When in a time crunch, I've also had success boiling them until softened completely then broiling until browned (maybe 5-10 minutes).

For baking potatoes

• Don't just wash them, scrub them. Otherwise you're eating dirt. No, that's not a joke. Potatoes grow in dirt, and are usually sold coated with dirt. Yes, really.
• Either salt them and wrap them in tin-foil, or simply bake them on a bed of salt. Dessication of the skin is important.
• You'll probably want to bake them longer and higher than most recipes say. I find 425F for 1 1/2 hours is optimal (and 2 hours is fine). That results in skin which is dry, crispy, and slightly caramelized, while this inside still is fluffy (albeit, according to some, overcooked).