Preheat the oven to 180 degrees lower and upper heat.
Peel and wash the vegetables, cut into pencils about the size of a finger. Blanch in hot water for about 2 minutes, rinse and pat dry. Mix with the oil and thyme and season with salt and pepper. Spread on a baking sheet lined with baking paper and bake in the oven for about 30 minutes until golden brown. Turn in between. Towards the end of the baking time, increase the temperature to 220 degrees and let the fries brown.
Tip: If you like it spicier, you can season the vegetables with chilli.