Prepare the asparagus. Snap off bases of spears and discard. Bring a small amount of salted water to boil in a saucepan, add a splash of lemon; add asparagus and cook until tender. Remove asparagus and shock in an ice bath to stop the cooking and to keep its bright green color.
Melt the 3 tablespoons of butter in saucepan. Add 1 tablespoon sesame seeds and cook, stirring 2 to 3 minutes over moderate heat, until lightly browned. Add 1 tablespoon lemon juice, 2 tablespoons orange juice, drizzle with 1 teaspoon of sesame oil. Whisk to make sure it's fully emulsified. Add salt, to taste. Add asparagus to sauce, and toss until coated. Serve hot and garnish with extra sesame seeds, if desired.