Preheat oven (electric cooker: 225 °C/circulating air: 200 °C/gas: level 4). Halve, clean and wash the peppers. Place on a baking tray lined with baking paper and roast for 8-10 minutes. Cover the bell peppers with a damp kitchen roll, allow to cool briefly and remove the skin.
Let the peppers cool down. Season with salt and pepper.
Clean, wash and pat dry the spring onions. Crush the sardines and some marinade oil with a fork, season with salt and lime juice.
Cover each 1⁄2 pepper with 2 spring onions and spread the crushed sardines on top.