Place water in a large pot and bring to a boil.
Add 1 tablespoon of salt and 1 teaspoon olive oil. Then add couscous. Cover, reduce heat and simmer for about 8 minutes, stirring occasionally.
Drain and rinse under cold water to stop the cooking process.
Place in a large bowl and drizzle with olive oil to prevent the couscous from sticking. Set aside to cool completely.
Once cooled, stir in the beans, corn, peppers and onion.
In a small bowl, combine all the dressing ingredients, mix well and pour over the couscous mixture. Toss together until evenly coated.
Cover and refrigerate for at least 30 minutes to allow the flavors to meld together. For best results, refrigerate overnight.
Serve with tortilla chips.