Preheat your oven to 220°C.
Cut the scrubbed sweet potatoes into thick wedges and place them in a large mixing bowl.
Cut the white potatoes into slightly thinner wedges and add them to the bowl.
Toss the potato wedges with thyme, cumin, chilli flakes, olive oil, and smoked paprika until evenly coated.
Season with sea salt and spread the wedges in an even layer on a non-stick baking tray.
Arrange sweet potatoes in the center and white potatoes around the edges of the tray.
Bake for 20 to 25 minutes, turning occasionally until cooked through and golden.