Set the oven to 200°C.
Cut the sweet potatoes and onion into cubes.
Rinse the beans.
Add the potatoes on a sheet pan, drizzle oil and season with salt, pepper, thyme, and garlic powder. Roast in the oven for about 15 minutes.
Add the red onion and beans, and roast for another 5 minutes.
Add the green kale to the warm veggies and mix around.
Mix the yogurt and mustard together and drizzle the dressing over the vegetables before serving. Garnish with some fresh parsley.