Spinach Salad

5 slices lean bacon, chopped fine 
2 tablespoons minced onion 
1/2 cup cider vinegar 
1/2 teaspoon sugar 
1 teaspoon Dijon mustard 
1 tablespoon olive oil 
Salt and pepper 
1 pound fresh young spinach, coarse stems discarded and leaves washed well and spun dry
1 hard boiled egg
parmesan cheese

In a large skillet, cook bacon over moderate heat, turning it, until it is crisp, transfer it to paper towel lined plate to drain, and discard all but 2 tablespoons of the fat. In the remaining fat, cook the onion for 1 minute. Add the vinegar, sugar, mustard, oil, and salt and pepper to taste. Bring to a boil, pour over spinach and toss. Serve sprinkled with the bacon, parmesan cheese and crumbled hard boiled egg.