Break off the tough ends of the asparagus and, if they're thick, peel them. Place the asparagus on a baking sheet, drizzle with olive oil, then toss to coat the asparagus completely. Spread the asparagus in a single layer and sprinkle liberally with salt and pepper.
Bake asparagus 12 minutes in the preheated oven, or until tender.
Melt the butter in a saucepan over medium heat. Remove from heat, and stir in soy sauce and balsamic vinegar. I add a little sugar, we like things a little sweet. Pour over the baked asparagus and serve.