Put the sliced onion in a mug with ½ cup water. Cover with a saucer and microwave for 2 minutes. Put onions and all the other washed and chopped vegetables into the rice cooker and cover with hot water. Press “cook”. When it is finished, test to see if the potato and the pasta are cooked. If not, press “cook” again. When all the vegetables are cooked, add salt (optional) and 2 Tablespoons of butter.