To make the crisps, turn the oven down to 200C/ 180C fan/ gas mark 6. Season the grated Parmesan with a large pinch of black pepper and scatter evenly over a baking tray covered with a silicone sheet or lightly oiled greaseproof paper and bake for 5 minutes, until golden but not browned. After cooling for five minutes, break into crisp pieces with your fingers.
Turn the oven up to 220C/ 200C fan/ gas mark 7. Toss the vegetable chunks in the lemon juice and oil, season lightly with salt and pepper, and bake in a roasting tin for 20 minutes. Add the capsicum wedges and continue to bake for a further 25 minutes.
Meanwhile bring a litre of water, salt and half the olive oil to a simmer in a large pot, then slowly add the polenta in a fine stream, stirring all the time. Continue to simmer over a low heat for 35 minutes (or according to the instructions if using quick cook polenta), stirring often to prevent it sticking to the bottom.
The polenta should be thickened but still soft at this point. If it starts to dry out too much, add a cup of water. When cooked, stir through the rest of the oil, the Parmesan and Taleggio and a pinch of white pepper.
To serve, spoon the polenta over a board or onto plates, scatter over the vegetables and any roasting juices, then the rocket and thyme. Tuck the parmesan crisps in between the veg, and eat hot.