Rinse and chop the rhubarb into small pieces.
In a medium-sized saucepan, combine the rhubarb, sugar, crushed cardamom pods, lemon juice, and water.
Heat the mixture over medium heat, stirring occasionally until the sugar dissolves and the rhubarb starts to soften, about 5-7 minutes.
Lower the heat and let it simmer for another 10-15 minutes, stirring occasionally, until the rhubarb breaks down and the jam thickens.
Taste and adjust sweetness if needed. Remove the cardamom pods for a smoother jam.
Once done, transfer the jam to a sterilized jar and let it cool completely before storing in the fridge.