hi jerry try the original V-slicer. it is a little expensive but oyu get all the gadgets with it and compared to the imitations that you used to be able to get in woolies. i know wilkinsons do one for 5pounds. alternatively use your multichef to finely cut the onion and pepper. when you say that restaurants would not pre fry the onion and peppers i would disagree remember that the scale they are cooking on anything they can prepare in advance they do, use your fryer or do them in the pan you are cooking with shallow frying until coloured at the edges.
some birs boil the above in water and turmeric and salt for 30 mins until soft.
btw the guy who demonstrates the v-slicer goes to all the county shows and has been on ideal shopping channel doing these in a deal with them says it it is the fastest chipper in the world, sad as it may sound i could watch him do the demos for hours and have done as it used to be in a loop on 1 of the tv channels after normal programming has finished ;D
regards
gary