1. Heat oil in a 12-inch nonstick skillet over moderately high heat until hot but not smoking and saute corn, stirring, until hot, about 2 minutes. Add onion and jalapeno and cook, stirring until onion is just tender, about 1 minute. Transfer to a bowl and season with salt and pepper to taste.
2. Stir beans together in another bowl with cumin, 1 tablespoon juice, and salt and pepper to taste.
3. Halve avocado lengthwise, discard pit and scoop flesh with a spoon from skin onto a cutting board. Cut avocado halves lengthwise into slices and crosswise into 1/2-inch cubes. Gently toss avocado in a small bowl with remaining 1 tablespoon juice an cilantro and salt and pepper to taste.
4. Set out 12 small (4- or 5-oz. capacity) plastic cups and layer ingredients beginning with corn mixture, then bean mixture, salsa, cheese, sour cream, and avocado mixture. Garnish tops with red onion and tortilla chips. Serve remaining tortilla chips in a bowl on the side.