In a large skillet, cook bacon over medium heat until crisp. Remove to paper towels with a slotted spoon; drain, reserving 2 tablespoons drippings.
In a large bowl, combine the arugula, eggs, leek, tomato and radishes. In a small bowl, whisk the vinegar, mustard, sugar, pepper and reserved drippings. Drizzle over salad; toss to coat. Sprinkle with bacon.