Hearts Of Palm, Heirloom Tomato And Avocado Salad

A bright, fresh and simple Summer salad!
Serves 2-4

1 cup mixed color heirloom tomatoes, chopped into ½-inch pieces
1/2 small sweet onion, cut into thin slivers
1 14-ounce cans hearts of palm, drained and sliced 1/2 inch thick
1 avocado, cut into 1/2-inch pieces
1/4 cup coarsely chopped cilantro
1/2 teaspoon finely grated lime zest
2 tablespoons freshly squeezed lime juice
2 tablespoons mayonnaise
2 tablespoons canola oil
Salt
Freshly ground pepper