Melt In Your Mouth Beef Tips with Mushroom Gravy

Ingredients
3 tablespoons butter
2 lbs sirloin beef tips
2 tablespoons all-purpose flour
1 white onion, diced
8 oz sliced cremini mushrooms
2 teaspoons garlic powder
1 teaspoon onion powder
1 teaspoon dried thyme
1 teaspoon dried rosemary
1 beef bouillon cube
1 tablespoon Worcestershire sauce
1 bay leaf
1/2 cup sliced pepperoncinis
1 1/2 cups-2 cups beef stock
2 tablespoons cornstarch
Kosher salt and freshly ground black pepper, to taste
How To Make Melt In Your Mouth Beef Tips with Mushroom Gravy