Step 1Toast seeds in dry skillet over medium heat, shaking pan constantly until seeds are golden, about 5 minutes. Set aside.
Step 2In large bowl, toss apples, onions and celery with juice of 1 lemon to keep apples from darkening. Set aside.
Step 3Blend together mayonnaise, tahineh, honey and remaining lemon juice; the mixture will be very thick. Toss with apple mixture. Cover with plastic wrap and chill at least 1 hour.
Step 4Just before serving, place spinach in large bowl, add apple mixture and toss to coat spinach thoroughly. Garnish with sesame seeds.