Add all ingredients to a blender and puree until smooth. Taste, and add more salt as needed. Set aside (refrigerate if making ahead).
assemble the salad
General note: if your bowl is wide, ring your ingredients against the glass and fill the center with romaine lettuce as you build the layers. This creates a nice balance of greens to veggies when you spoon down into the bowl.
In a medium glass salad bowl (about 90 ounces), spread a thin layer of romaine lettuce. Spoon black beans over the lettuce. Add red onions over the black beans, followed by a layer of olives, then corn, avocados, bell peppers, and top with cherry tomatoes.
Sprinkle herbs over the cherry tomatoes.
If you're not using romaine lettuce to fill the center of the bowl, serve lettuce in a separate bowl tossed lightly with extra virgin olive oil.
Serve the creamy salsa vinaigrette dressing on the side.