Break off the woody white parts of asparagus and lay them over on a baking sheet. Drizzle the olive oil and season with salt and pepper lightly. Roast the asparagus for 10-15 minutes depends on their thickness until they are crisp tender.
Meanwhile, melt the butter in a small sauce pan over low heat and brown until it turns deep golden brown, about 3-4 minutes. Remove the pan from the heat. Spoon up the foam on the top and discard. Mix in balsamic vinegar and soy sauce.
When the asparagus is roasted, drizzle the sauce over and toss well. Serve warm or at room temperature.
Notes
Look for rather thick asparagus. Thin asparagus is not suitable for roasting and they can be mushy not crisp tender after roasting.