STIR-FRIED MTV was added to the menu at the Food Fare in Pacific Place yesterday when video jocks Angela Chow and Rita Tsang dropped by to remind the lunchtime crowd that as of tomorrow the popular rendezvous will be open until 10 pm. What's more, MTV will be served up on a giant screen with the luscious Angela, Rita et al certain to titillate appetites. ''When I'm appearing on screen I'll make it a point to wear warm colours,'' said Angela. ''They make you hungry.'' See, there's something new to be learned every day.