Tuna Avocado Zucchini Boats

 1/2 can (6.5 oz), drained Tuna in Water (Canned)

 1 dash Black Pepper

 0.125 cup Yellow Mustard

 1 dash Salt

 1/4 avocado, NS as to Florida or California Avocados

 1 stalk, small (5" long) Celery

 1/4 cup, chopped Scallions or Spring Onions

 1 medium Zucchini

 0.125 serving (serving = 1 cup) Kroger Plain Greek Yogurt