In a large skillet, preferably one that doesn't stick, put the spoonful of oil and when hot add the potatoes with a good pinch of salt. Leave them there until they are golden brown on one side.
Add the onion and garlic for about five minutes, add the chorizo and leave for 7-10 minutes more. The potatoes should be soft, and the chorizo well cooked. Taste and adjust for seasoning if necessary.
Meanwhile, the potatoes and chorizo cook, prepare the bread by slicing it in half. Spread vegan crema or vegan mayo across the tops and bottoms of the ciabatta.
Top the bottom of the ciabatta roll with a spoonful or two of the potato-chorizo mix, the top that with lettuce and gently press the tops bun over.