Heat the oven to 130C fan/gas mark 2.
In a small saucepan, reduce the lemon juice on a high heat for 3 minutes until only 1½ tablespoons remain, then tip into a bowl.
Melt the butter in a small saucepan on a high heat, then strain through a fine-mesh sieve into the lemon syrup bowl (discard the butter solids).
Stir in the almonds, lemon strips, herbs, syrup and 1¼ teaspoons of salt, then spread out on a 30cm x 40cm oven tray lined with baking paper.
Roast for 18-20 minutes, stirring from time to time, until the nuts are golden-brown and the herbs and lemon are crisp.
Stir in the oil, sumac and chilli, roast for 3-4 minutes, until a deep golden-brown, then leave to cool before serving.
