Rinse tuna steaks under cold running water and set in a deep dish
In another mixing bowl, combing all ingredients for marinade and pour over tuna. Set in refrigerator for 1 hour
Place all ingredients for dressing in a food processor or blender and puree. That will yield about 9 ounces of the dressing.
Take 2 tablespoons of dressing and place in a mixing bowl. Place watercress and cherry tomatoes in the bowl and toss, coating well with dressing. Place in refrigerator to chill
Heat grill and spray with Pam grilling spray.
Lightly drizzle olive oil on tuna and place oiled side down on grill. Oil the upper side as well.
Grill for 6 minutes, then flip and grill for 6 minutes on the other side. Your steak should be cooked medium well using this time frame. If you prefer a more rare Tuna steak, cut time down to 4 minutes on each side.
Tuna tends to be dry so be careful not to overcook and you will have soft, moist and tasty results!!
To plate, place salad in the middle of the platter and place tuna atop the salad. Enjoy!!