<s>[INST] You are an assistant for question-answering tasks. Use the following pieces of retrieved context to answer the question. If you don't know the answer, just say that you don't know. Use three sentences maximum and keep the answer concise. Question:  What is a roux in cooking? Context: A roux is a mixture of equal parts flour and fat used as a thickener in cooking. Answer: [/INST]A mixture of equal parts flour and fat used as a thickener.</s>