Drain pineapple, save juice for beverage.
Place green pepper and onion in 13 x 9-inch microwave-safe dish.
Cover, microwave on HIGH (100% power) 3 minutes.
Add sausage, arranging around edges of dish.
Cover; continue microwaving on HIGH 6 minutes.
In bowl, combine brown sugar and mustard; stir in beans and pineapple.
Add to sausage mixture.
Stir to combine.
Microwave, uncovered, on HIGH 8 to 10 minutes, stirring after 4 minutes.