They are definitely best just heated in the boiled water. I microwave them every once in a while when in a hurry, and grill them whenever I'm *insane* and forget that this is a very bad thing to do. They come out hard and rubbery.
The smart dogs DO have a "grillers" version but I dont think that its vegan. I think I tried it once and didn't like it as much. I liked the morningstar farms hotdogs the most for tasting like "real" hot dogs, but they have egg in them and have a TON of sodium. I stopped buying them when I found this vegan version. I was looking for a hotdog with lower sodium for my father and the litelife ones are the lowest out of all hotdogs, real or fake - and at over 300mg a dog, its still really high, especially since my father is limited to 750 mgs a day!!!