In a jar with a tight-fitting lid, place all dressing ingredients. Shake until combined. In a bowl, toss salad ingredients together. Set both aside.On a plate, combine sesame seeds and garlic powder. Press both sides of each tuna steak into the mixture. Heat oil in a large nonstick skillet on medium-high. Sear tuna to desired doneness, turning once, 2 to 3 minutes total for rare or 3 to 4 minutes total for medium-rare.Divide salad among plates; drizzle lightly with dressing. Slice tuna, arrange over salad and drizzle with additional dressing. ( Tip : If using our Meal Plan, store components separately in the fridge. Dress right before eating.)