Boil the vinegar over high heat and uncovered, for 10-15 minutes - Until it is reduced by half. Roast the nuts in a dry pan over a moderate heat for 2-3 minutes. Let the nuts cool on a plate. Fry the bacon for about 10 min. until it is golden and crisp. Let it drain on paper towels. Leave half of the bacon fat in the pan and fry the spring onions for about 2 min. Arrange spinach, lettuce, bacon, onions, walnuts and blue cheese on a platter.
Pour some balsamic vinegar over the salad and garnish with violets.
Serve with bread.