Add chicken to a large resealable bag or bowl. Add 2 tablespoons oil, 2 tablespoons vinegar, 1/4 teaspoon of salt and pepper, and toss until chicken is coated. Allow it to marinate for 10 minutes, turning occasionally.
Meanwhile, divide the spinach, chopped pecans, crumbled feta cheese, sliced strawberries, and avocado among four plates or bowls.
Add all ingredients for the dressing to a blender and blend until smooth.