Twist off beetroot (do not remove roots). Wash beetroot and cook in boiling salted water for about 20 minutes. Drain, rinse with cold water, peel and slice. Pour boiling water over the onions, leave to stand briefly, drain and peel
For the infusion bring sugar, 750 ml water and vinegar to the boil and simmer for about 5 minutes. Season with laurel and 1 pinch of salt. Wash lemon hot, grate dry and cut into 5 slices
Put the beetroot and pearl onions into clean, previously hot rinsed preserving jars. Pour the infusion evenly into the glasses. Put 1 lemon slice in each glass. Close the glasses tightly. Preheat the oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: see manufacturer). Place the oven pan in the oven, place the glasses on top so that they do not touch each other and pour boiling water about 2 cm high
If air bubbles start to rise in the glasses, reduce the oven temperature (electric cooker: 100 °C/ circulating air: 75 °C/ gas: see manufacturer) and boil down for another 30 minutes
Allow glasses to cool and store in a cool and dark place. Shelf life at least 6 weeks and longer
Preparation time approx. 2 hours