Place the potatoes in a large saucepan, cover with cold water and add salt. Cover, bring to a boil and continue to boil 12 to 15 minutes until the potatoes are cooked al dente (cooked through but not overdone). Drain and set aside.
In a large bowl combine the yellow pepper, mesclun lettuce and calamata olives. Add the roasted onion and tomato.
When the potatoes have cooled down a bit, slice them into small chunks. Add the potatoes to the vegetables in the bowl, and pour the vinaigrette on top. Gently toss to coat. Season with salt and pepper to taste and serve at room temperature (or save in the refrigerator for up to 2 days).
Put all the ingredients in a blender and mix at medium speed until well-blended.
Recipe courtesy of Rafael Palomiro, Sonora Restaurant, New York, NY