Whole Brussels sprout leaves make beautiful little salad greens. If pressed for time, slice the sprouts instead of peeling.
Remove and discard stem ends from Brussels sprouts; peel leaves, and place in a large bowl. Add apple slices.
Place bacon in a single layer in a large cold skillet. Cook bacon over medium heat 4 to 5 minutes on each side or until crisp. Remove bacon, reserving drippings in skillet. Add cooked bacon to Brussels sprouts mixture.
Add vinegar to skillet, and bring to a boil over medium heat, stirring to loosen browned bits from bottom of skillet. Boil 1 minute or until reduced to about 1/3 cup, stirring occasionally.
Stir in mustard and next 4 ingredients. Add oil in a slow steady stream, stirring constantly, until blended. Remove from heat, and stir in lemon juice and sugar. Pour hot dressing over Brussels sprouts mixture; toss. Season to taste with salt and pepper; serve immediately.