Pre-heat the oven to 180 degrees C.
Place the sauce onto the pizza base and spready evenly.
Add the cooked sweet potato slices, red onion, bell pepper, vegan cheese and balsamic vinegar to the pizza and cook in the pre-heated oven, on a suitable baking tray or pizza stone, for 12 minutes.
To make the gremolata, simply mix the finely chopped kale, garlic and lemon zest together in a small bowl.
After 12 minutes, remove the pizza from the oven and sprinkle on the kale gremolata. Return the pizza to the oven for 3-5 minutes until the gremolata is turning crispy, but not burnt.
Slice and serve!