In a small bowl add egg yokes. Whisk until frothy.
Add red wine vinegar and lemon juice. Mix well.
Add olive oil. Mix well.
Add honey, tarragon and Dijon mustard. Mix well. Set aside.
Add bacon grease to a large skillet. Place over medium heat.
When grease is hot, add onion. Sauté for about 2 minutes.
Add mushrooms. Sauté until onions are soft and fragrant.
Add egg mixture to skillet with the onion/mushroom mixture. Mix well.
In a small cup, mix cornstarch and water.
Add your water mixture to the onion mixture. Increase heat slightly and bring to a boil. Dressing will thicken. Reduce heat to warm.
Keep warm and stir occasionally until ready to serve.
Store leftovers in a tightly sealed container, in the refrigerator, up to a week. Reheat before serving.