Mix 2 tsp. of cornstarch with 2 tsp. of water in a medium bowl. Set aside.
Fry bacon until it can be crumbled. Remove bacon leaving drippings. Add onion to bacon fat and cook until tender. Remove onion with slotted spoon and add to bacon, leaving fat.
Pour slightly cooled bacon fat into a measuring cup and add vegetable or canola oil to measure 1/2 cup. Blend with cornstarch mixture and set aside.
Combine vinegar, water sugar, salt and pepper in a small saucepan and heat to a gentle boil. Add cornstarch mixture gradually and slowly cook 1-2 minutes until thickened.
Remove from heat and add bacon and onion. Toss with spinach, lettuce or a mix of your favorite greens while warm. Top with sliced hard boiled egg and croutons for a dinner salad or a poached or fried egg for a wonderful light lunch.