Heat the oil in a frying pan, briefly sauté the onions, add the peppers and cook for approx. 5 mins. Add the tomatoes, season, cover and simmer for approx. 25 mins.
Spread the bread with oil, toast in the same frying pan until golden brown.
Bring the water and vinegar to the boil, reduce the heat. Crack the eggs one at a time and carefully slide into the simmering water, cook for approx. 4 mins. Remove, drain, serve on top of the peperonata, garnish with the reserved spring onion greens and fleur de sel. Serve with the bread.