Fully thaw blueberries and place them along with remaining dressing ingredients into a food processor or blender; blend well. Place into a sealable container, and into the refrigerator until ready to serve.
Chop tomatoes; peel and slice carrots. Toss with greens in a large bowl. Roughly chop walnuts and add them along with feta to bowl of veggies.
When ready to serve, toss with dressing and serve with whole grain crackers.