To marinate the red onions, whisk rice vinegar, salt and sugar. Stir to dissolve salt and sugar. Toss with sliced onions. Let marinate for 1-2 hours in refrigerator.
For the Exclamation Sauce, whisk yogurt and olive oil together. Set aside.
To assemble the salad, gently rinse and dry watercress in salad spinner. In a large bowl, whisk lemon juice, olive oil and dill. Just before serving add watercress, berries and onion mixture and toss gently. Divide between 3 plates and spoon a dollop (about 2-3 tablespoons) of the Exclamation Sauce on the side of each plate. Run the tip of the spoon down the sauce to create exclamation!
Nutrition content of this recipe is calculated by a registered dietitian nutritionist. Due to variations in ingredients and measurements, values are approximations. Nutrients provided for this recipe represent values based on the best available information. This information is not intended to treat or diagnose. Please consult your physician for diet recommendations specific to your personal needs.