Black Garlic Tamarind Reduction
Combine beef stock, tamarind paste and black garlic in a small pot over medium-high heat. Bring to a boil and lower to a simmer.
Add soy sauce and white sugar and let simmer for 3-5 minutes. Add salt and pepper to taste.
The sauce will start to reduce, watch closely for about a minute. Sauce is ready when it coats the back of a spoon completely.
In a medium saucepan, add oil and butter over medium heat until foaming.
Add onions, garlic, salt, pepper and cook, stirring occasionally, until softened and liquid has evaporated.
Stir in cream and tarragon. Simmer for 3-5 minutes.
Transfer hot onions and cream to a blender, blend on low and gradually increase to high, until a smooth consistency is formed. Remove and strain into a container.