This homey dish can be prepared in under an hour, not including soaking time for the cashews. You'd never guess it was so simple because the flavors are so complex!
Add drained and rinsed cashews to a blender and set aside.
In a large skillet or cast iron pan, heat butter (or ghee) and oil of choice.
Add diced onion and saute for 5 to 7 minutes, until soft.
Add crushed garlic and stir.
Transfer garlic and onion to the blender with the cashews, add 2 cups of broth to start, and begin blending.
Blend on high speed until the gravy is smooth and without lumps.
Transfer the gravy back into the skillet.
Add vinegar, tarragon, salt, and pepper. If thinner gravy is desired, add additional broth.
Reduce heat to low and keep warm.
Serve over Tarragon-Dijon Meatballs.