Place the teabags into a cup, pour over the boiling water and leave to infuse for three minutes.
Remove the teabags and pour the tea-infused water into a small saucepan. Add the orange juice and brown sugar and place over a high heat. Simmer for six minutes, or until reduced by half.
Add the plums to the syrup and simmer for 1-2 minutes.
To serve, pile the watercress onto a serving plate and pour over the plums.