Brown the onions in a moderately hot oil in a large skillet. Add vegetables one at a time sauteeing each one for a minute or two before adding the next. Stir in tomato sauce & about a cup of water. Reduce heat & simmer till all the vegetables are tender.
Spoon out half a cup of the broth & mix it with the peanut butter to make a smooth paste. Return to the pot & simmer for 15 minutes. Serve over rice.