Add the arugula and spinach to a large platter and gently mix to combine the greens. Layer the thinly sliced red onions, sliced strawberries, diced avocados, toasted pecans, and the crumbled goat cheese.
4 cups baby arugula, 2 cups baby spinach, 1 1/2 cups strawberries, 1/4 cup red onion, 1 medium avocado