1 med. cauliflower
1/4 c. water
1/2 c. mayonnaise
1 tsp. onion, finely chopped
1 tsp. prepared mustard
1/4 tsp. salt
1/2 c. shredded cheese

Place cauliflower and water in 1 1/2 quart glass casserole. Cover with glass lid. Microwave for 9 minutes on high; drain.

Combine mayonnaise, onion, mustard and salt in small bowl. Spoon mustard sauce on top of cauliflower; sprinkle with cheese. Microwave for 1 1/2 to 2 minutes on roast to heat the topping and melt the cheese. Let stand for 2 minutes before serving.