Beef Steak with Onion Sauce

Ingredients:
- 2lb beef sirloin
- 2 tbsp butter

- 1/2 yellow onion, peeled and wedged

- 1 cup shallot, peeled and wedged
- 1 clove garlic, halved
- 1/4 tsp ground pepper
- 1/4 tsp tarragon
- 1/4 tsp rosemary
- 1 cup beef broth
- 1.5 tsp gluten-free rice vinegar (optional)
- 2 tbsp red wine (optional)
- 1 tsp salt
- 2 tbsp corn starch

Preparation:
- Heat butter on medium heat in a skillet. Sauté garlic and onion until aromatic.
- Add beef and brown the meat. Then add tarragon, rosemary, ground pepper, beef broth, rice vinegar, red wine, and salt. Boil the sauce and then simmer for 30 minutes.
- Mix corn starch with 2 tbsp water and whisk into the sauce. Continue to simmer for 20-25 minutes until the sauce thickens.