Peel the sweet potatoes and cut into sticks (approximate french fries size). Transfer to a large bowl.
In a small bowl, mix the polenta, cornstarch, smoked paprika, and olive oil to a paste. Add to the sweet potatoes and mix well with your hands so that the sweet potatoes are evenly marinated with the paste.
Place the fries evenly and preferably without overlapping each other on a baking sheet lined with baking paper and bake on the middle rack for about 20 minutes. Move or turn the fries and bake for another 5–10 minutes until they are well browned. At the end of the baking time, the fries are still a bit soft, but they get crispy as soon as they come out of the oven and onto the plate. Take the fries out of the oven and season with salt.
In the meantime, prepare the avocado dip. If you don't tolerate raw garlic, you can briefly fry the chopped garlic in a pan with a little olive oil and then process it together with the avocado pulp and the other ingredients in the food processor to a fine cream. Serve the dip in a small bowl with the fries.