Preheat the oven to 180°C/350°F/gas mark 4.
On a baking tray, drizzle olive oil over the sweet potato pieces and sprinkle with salt and pepper. Place in the oven for 30-40 minutes until the sweet potatoes are cooked – they should be soft and caramelised.
Cover the walnut pieces in the maple syrup and place on a baking tray in the oven for 5 minutes, until lightly toasted.
Meanwhile, tear the kale into bite-size pieces, removing and discarding the fibrous stems, and place in a large bowl. Add into the bowl the avocado, tahini, lemon juice, cayenne pepper and tamari.
Using your hands, massage all these ingredients into the kale for a few minutes. This process breakdowns the kale tough cellulose structure. You will notice the kale will shrink in size, become darker, and have a softer texture (The longer you leave the kale, the softer and easier to chew it will become – you can leave it for up to 2 days or eat right away).
To serve, combine the kale mixture with the sweet potatoes and walnut maple pieces.