It's the semi-finals. The past five weeks have seen the chefs whittled down to the best eight. Now, it's all about survival as they battle for a place in the last six.Limiting food waste should be at the forefront of every chef's mind, so first up, the semi-finalists will be asked to create one dish which embraces either 'root-to-shoot' or 'nose-to-tail' eating. The professionals will choose one ingredient and serve it in as many innovative and exciting ways as they can, showing total respect for the produce selected.The judges will then pick the contestants worthy of going straight through to the next round, leaving the others to face an invention test that will have them cooking for their MasterChef lives. Each professional will need to pick a box, under which lies a mystery seafood ingredient. Using the larder to complement it, they will need to create a dish that showcases and celebrates that ingredient.The two who fail to hit the high notes will be sent home, leaving the rest with a one in six chance of becoming this year's champion.