Melt butter in a small skillet and add yellow and green onion. Saute until they are tender. In a separate medium sized saucepan, bring beef broth to a boil and add whipping cream. Reduce heat to a simmer. Add peppercorn, thyme, and sauted onion. Stir. Remove from heat. Serve in a side cup for dipping, or drizzle over fresh from the grill steaks!