Mix the apples and lemon juice in a pan, cover and simmer over a medium heat for approx. 20 mins. until soft, then puree.
Mix the squash, polenta, flour and sage in a bowl, season with dukkah and salt. Whisk together the milk, oil, eggs and garlic, mix into the squash mixture.
Heat the oil in a non-stick frying pan. Pour as much batter into the pan as it takes to make fritters of approx. 7 cm in diameter. Reduce the heat, cook for approx. 2 mins. until the underside separates from the pan. Turn the fritters, cook for a further 2 mins., cover and keep warm, repeat these steps with the remainder of the batter.
Whisk the vinegar, oil and yoghurt in a bowl, season. Mix in the lamb's lettuce, serve with the squash and polenta fritters and the apple sauce.