Most tapas restaurants have these on the menu but if you fancy making them at home, Waitrose** at least definitely stocks them.
**And Lidl and M&S too apparently!
Ingredients (makes enough for a tapas style dish, or starter for two):
1 bag Padron peppers (150g)
Heat a good glug of olive oil in a frying pan.
Cook the peppers over a medium-high heat for 3-4 minutes, until the skin starts to blister.
Put the peppers into a serving bowl and sprinkle with sea salt.
Watch out for the hot ones!