In a 3 quart casserole, snip the bacon into 1-inch pieces. Cover with a paper towel and micro cook on High (100 %) for 2 to 3 minutes or until crisp. With a slotted spoon, place the bacon on a paper towel to drain. Add the vinegar, sugar, salt, pepper, and tarragon. Micro cook on High (100 %) for 2 to 3 minutes or until the mixture boils. Remove from the oven and stir in the celery and onion. Gradually add the torn spinach and toss lightly to coat each piece. Add the cooked bacon, orange segments and cashews. Toss lightly to coat, then serve immediately.