Method:
To make the dressing, combine all ingredients in a blender and blend until smooth. Taste and adjust seasoning and thin to desired consistency with additional orange or lime juice. Transfer to a bowl and set aside.
For the salad, place onion slices in water, add a few ice cubes and let sit for at least 15 minutes before serving. When ready to assemble salad, pour off water and drain onion thoroughly. Soaking the onion in water will reduce its sharpness.
To serve, arrange greens on a platter or in a large salad bowl. Arrange onion, hearts of palm, bell peppers, avocado, black beans, corn and cashews in sections on top of the greens. Stir dressing to recombine and serve alongside salad.