Translated from Karlos Arguiñano's "Atrévete a cocinar". I've never found green peppers like the fine ones in Spain. They look much like poblanos but they're not spicy in the least, and they don't taste as strong. Red bell peppers might make a good substitute. Spring onions in Spain are about the size of a small regular onion in the US. I would use maybe 4-6 green onions if I'm in the US. The author doesn't recommend measuring equipment, so a tbsp means a soup-spoonful.