For years, I have loved padrón peppers, originally from the town of the same name in Galicia in far northwestern Spain. I've eaten these delicious treats at a few select tapas bars over the years, but padrón peppers are still really hard to find in the US. We are lucky to have a couple of growers here in Virginia and a couple more on the east coast from whom we can source them each summer. As you can see from the photo, they are small green fairly nondescript peppers.
The reason they are so highly prized as a tapa is that when fried in a little olive oil and sprinkled with sea salt as in the photo below, they are absolutely delicious. But there's a catch. You play Spanish roulette with these peppers: most are mild as they can be while some are pleasantly spicy (but not quite as spicy as a jalapeño). I've found that the older (i.e., larger) and more drought-stressed the peppers are, the spicier they are. This batch seems to be running about 20% spicy and 80% mild.
They're worth growing at home if you can find seeds and if you ever see them on a restaurant menu, worth eating.