Peel the sweet potato, and cut it into 1cm dice. Toss in 1tbsp of oil, the smoked paprika, and a little salt and pepper. Spread out into a single layer on a baking tray, and roast for around 35 minutes at 190°C (Gas Mark 5 / 375°F), until soft in the middle and slightly crispy on the edges.
Meanwhile, remove the tough stems from the kale, and cut the leaves into strips. Heat the remaining 1tbsp of oil in a large frying pan, and add the kale and garlic. Cook over a medium heat for a few minutes, then add the cooked rice and pine nuts. Cook for a few more minutes so that they can absorb the garlicky flavours and become slightly toasted.
When the sweet potatoes are ready, add them to the rice and kale, and mix well. Serve warm.