Cook the pasta in 2 cups of water with 1 tsp olive oil & salt. Drain the water completely & let it cool.
Beat the yogurt well and add 1 tsp olive oil, mustard powder/paste, sugar, pepper powder & salt. Combine well. Add the cooled pasta and veggies. Mix well so that the pasta and veggies are coated with the yogurt dressing. Refrigerate for 2 hours, serve chilled.
For the healthier version, use brown/organic pasta and no/low fat yogurt.
* You can use any veggies that you like, though I strongly recommend capsicum and celery since it gives a special flavor. I have used carrot, cucumber, capsicum, spring onion, celery & lettuce.
Notes
Update on 25th Feb 2013: I made pasta salad recently with the addition of black olives and some Italian seasoning. I used red and yellow capsicum to make it colorful. Also for the dressing you can use a combination of mayonnaise (eggless mayo will do) and sour cream. Another dressing option is fat free mayo and fat free cream cheese (full fat version is also great). You can mix and match the dressing and ingredients to suit your taste preferences.