Heat the oven to 400 degrees.In 30 cm skillet,over medium high heat, heat 1 tablespoon. vegetable oil;add onion and chili powder;cook about 10 minutes,stirring frequently,until onion is tender and coated with chili powder.Remove onion to large bowl;wipe skillet clean.To bowl with onion,add beef,egg,chilies,bread crumbs,1 tablespoon. of each of cheeses and salt;using hands or wooden spoon,blend well.Shape mixture into 3 cm balls.In skillet over medium-high heat,heat remaining 2 tablespoon. oil;add meat mixture;cook 15 minutes,turning frequently,until well browned on all sides and cooked through.Meanwhile,place tortilla chips in single layer on jelly-roll pan;bake 10 minutes until crisp and golden.Prepare Zesty Tomato Salsa.To serve:Spoon meatballs into center of large serving platter;sprinkle with remaining Monterey Jack and Cheddar cheese.Arrange tomato wedges and lettuce around meatballs if desired.Serve with tortilla chips and salsa.Makes 4 servings. ZESTY TOMATO SALSA: In a 2 litre saucepan over medium high heat,heat 1 tablespoon.vegetable oil; add 1 each red and green bell pepper,cored,seeded and diced (about 2 cups),1 medium size onion,diced (about 0.75 cup) and 1 large clove garlic,crushed. Cook about 10 minutes,stirring frequently,until tender.Stir in 2 large fresh,ripe tomatoes,diced (about 2 cups) and quarter to half tsp. hot red pepper sauce;cook 1 minute longer until heated through. Makes about 1.5 cups.