Peel and chop the garlic.
Mix the garlic with the oil, curry powder, cumin, paprika, salt and pepper.
Peel the sweet potatoes and cut into 2cm thick slices.
Toss the sweet potatoes in the spiced oil to coat evenly.
Place the sweet potato slices on a baking tray lined with baking paper. Bake in the preheated oven at 200°C (180°C fan, gas 6) for 35 minutes.
Just before the end of the baking time, halve the lemon and squeeze over the sweet potato slices.