In a large skillet bring 1-inch of water to a boil, add the haricots verts and simmer for 4 minutes or until just tender. Drain and refresh under cold water. Pat the haricots verts dry and chill them, covered, for 2 hours. Salt tomato halves and invert on rack and let sit for 30 minutes. In a bowl combine the vinegar, mustard, salt, pepper and Worcestershire, add the oil in a stream, whisking, and whisk the dressing until emulsified. Add the dill and combine. Arrange the haricots verts, tomatoes and cucumber slices decoratively on a platter, garnish the vegetables with the minced egg yolk and white and spoon the dressing over the salad.