Guindillas are long, thin green peppers from the Basque Country. They are pickled in white wine vinegar, which gives them a satisfying crunch. Whilst they are related to other chillies, they are comparatively mild with a spicy-sweet taste.
They are served as a side dish or on a gilda, a small skewered pintxo with olives and anchovies. Occasionally, they may be tossed in olive oil and garlic.