This week's seven best home cooks from the first round return to test their culinary wits and show judges John Torode and Gregg Wallace that they have the potential to be MasterChef champion 2022.Tonight's first task is the Market Challenge, with the seven having to invent a dish on the spot using a marketful of ingredients, including whole mackerel, squid and pork tenderloin.The pressure is on to impress because at the end of this test one contestant will be sent home. The remaining six then face their most demanding assignment so far - cooking a dish to a brief set by one of the country's toughest food critics, Grace Dent. Grace has asked them to cook a dish centred around one of her favourite ingredients, the humble potato.In a competition where only the food matters, and with just four places up for grabs, these amateurs will need to be good to make it through to the quarter-finals.