Add 1 tbsp chia seeds to a glass or jar.
Pour in 250-300 ml of warm water and stir well to prevent clumping.
Add 1 tbsp apple cider vinegar, the juice of ½ a lemon, and ¼ tsp ground cinnamon.
Stir again and let it sit for 5-10 minutes (to allow chia seeds to expand).
Stir once more before drinking.
