Heat oven to 400°F. In large bowl, stir together cereal, pretzels and peanuts; set aside.
In 1-quart saucepan, melt butter over medium-high heat. Stir in soy sauce, Worcestershire sauce and mustard. Pour over cereal mixture; stir until well coated. Spread on ungreased large cookie sheet.
Bake 15 to 20 minutes, stirring every 5 minutes. Cool completely, about 30 minutes. Store in large food-storage plastic bag, reusable container, or pretty glass jar.