Heat a little oil in a large frying pan and fry beef for a few minutes to warm through. Add kale and cook and stir for a few minutes until wilted and soft, or to taste. Season with salt and pepper to taste.
In a small bowl whisk together soured cream and taco seasoning.
Distribute kale and beef evenly over the 4 taco shells and add a spoonful of soured cream mixture. Serve immediately.