Mix the dry yeast with the beer, the chicken stock and the sugar well until everything is dissolved. Knead in the flour for 10 minutes until you have a smooth dough. Let rise for an hour covered in a warm environment.
In the meantime, cap the onion at both ends, peel and halve lengthways. Cut the halves lengthways into approx. 6mm thick slices and cut them crosswise in a block into 6mm wide pieces. Fry in a pan with the sunflower oil until light brown. Cut an approx. 4 cm long piece from a carrot, peel it, cut lengthways into thin slices and cut them lengthways into thin strips. Work the strips crosswise into small cubes. Weigh frozen goods and allow to thaw. Freeze unused goods.
Knead the dough and roll it out into an elongated flatbread. Brush the lower half with the onions and the frying oil, leaving a thumb-wide strip free on the left, bottom and right edge. Scatter the diced carrots over the onions. Press everything down a little. Roll up the flatbread from below.
Line a baking sheet with parchment paper and place the rolling pin on the paper with the end facing down. Score the rolling pin several times on the top. Brush with water and let rise covered in a warm place for 2 hours.
Preheat the oven to 200 degrees bottom heat. Place an ovenproof bowl with hot water on the lowest level. Bake the baguette on medium heat for about 30 minutes.
Let cool down a bit, cut and enjoy.