Melt 1 tablespoon butter in a large frying pan, and add the chicken, onion and a dash of salt and pepper, and cook on medium heat until the chicken is done, and the onion is translucent.
Add the mixed vegetables (optional) and cook until they are heated.
Slide the above mixture to one side of the pan and add ketchup to the other. Let it heat through just a bit and then mix both sides together.
Add the rice and continue to heat and mix it all together so that all of the rice has a light coating of ketchup (add a little more if needed - it should be coated, not soupy).
If using one pan, remove the rice mixture, set aside and clean the pan.
Melt 1/2 tablespoon of buttera and mix one egg with water, salt and pepper and then pour it into the pan, swirling it gently to cover the entire bottom. Let it continue to cook a minute or two until set.
Put half of the chicken and rice mixture on top of the very thin omelette, fold two sides (wings) toward the middle (it's OK if they don't meet!).
Place a plate face-down on top, hold the plate and invert the pan and lift it off so that the folded in wings are under the rice.
Repeat from Step 6 with the second egg and remaining rice mixture.
Serve with more ketchup, and make it fun by writing a message on the omurice or the plate.