Prepare farro according to package instructions. Place in a serving bowl and let cool while you prepare the other ingredients.
Prepare the dressing: In a small bowl, whisk together all of the ingredients until combined: olive oil, balsamic vinegar, honey, mustard, poppy seeds and salt. Taste and adjust seasoning as desired. Pour over the farro, then toss to coat.
Add the remaining ingredients to the bowl with the farro: strawberries, avocados, spinach, feta, red onion, and walnuts, then toss gently to combine. Serve chilled or at room temperature.
Strawberry Farro Salad tastes best the day it is made but can last 1 or 2 days in the fridge (the avocado will brown, but be safe to eat).