Pimientos del padron is a dish I see often in Spain used as one tipe of tapas among many others. I was lucky to get some of these in my local supermarket. The ones I ate in spain were always a kind of "Russian Spicy Roulette": you might eat 5 mild ones of them and then get an extemely spicy one, in fact, that's the fun of it, especially the people's face when they get the spicy surprise.
The ones I got weren't spicy at all, unfortunately, but good all the same.
Fast recipe too:
Heat up some olive oil in a pan and roast the peppers slowly, they may have some darker bits, no problem. Throw in medium sea salt in the end on the peppers. You can eat them hot or cold.