Spinach Salad

My sister-in-law, Jill, brought this salad to our family reunion last weekend.  She had mentioned this salad a few weeks ago at the extended Corbridge Reunion, which has had me anxious to try it ever since!  Jill said that she'd tried this salad at another reunion the month before and it was the talk of the menu.  She couldn't wait to get the recipe and when she finally did, she realized that it was a  recipe she was given at her own bridal shower twenty-some years ago.  She'd thought that the recipe sounded strange and had never made it before!  Now it's a favorite.  And I get why!  Holy Cow!  This is one great salad!!!

Salad

1 package bacon, cooked and crumbled
12 ounces swiss cheese, grated
2 large bags of fresh spinach
1 head of lettuce, choppped

Dressing

3/4 pound fresh mushrooms, sliced
1 medium purple onion, sliced thinly
1 1/2 Tablespoons poppy seeds
1 cup vegetable or olive oil
3/4 cup red wine vinegar
1/2 cup sugar
3/4 tsp. dry mustard
1 tbsp. onion salt

Mix the dressing and let sit for at least two hours.  Then, pour the dressing on the salad and toss and serve.  The dressing keeps in the fridge for a few days, if you don't want to toss it all at once, since the salad is so huge!   SO SO good!  Enjoy!