To make the pancakes, put the flour, peas, oil, turmeric, salt and pepper into a bowl and whisk together. Add 150ml of cold water and whisk to make a smooth batter. Set aside for one hour.
Combine all the dressing ingredients together in a bowl, adding a little water to thin down and cover with cling film and put in the fridge to chill.
Spread the chopped squash and onion in a single layer in a baking tray. Drizzle over the oil, then sprinkle the cumin seeds, garam masala and chilli flakes over the squash and onion, seasoning with salt and a little pepper. Roast for 25-30 minutes, turning the vegetables half way through until golden and tender. Take out of the oven and mix in the peas. Keep warm.
To cook the pancakes, heat a non-stick frying pan over a high heat and add a little of the vegetable oil. Turn the heat down to a medium heat and pour a quarter of the batter into the pan, swirling the pan so that the batter covers the base. Cook until the pancake sets, this should take around a minute, toss the pancake and cook for about 10 seconds longer. Transfer to a plate and keep warm by covering loosely with foil. Repeat with the remaining batter until you have 4 pancakes.
To serve, divide the roasted squash and red onion mixture between the pancakes and spoon over some dressing. Lightly fold the pancakes over and serve immediately.