Whisk all ingredients together except for watercress and sesame seeds.
Divide and pour into two ramekins.
Place ramekins in pot and put enough hot water in pot till it reaches half way up the sides of the ramekins.
Place cover on pot, preferably a transparent one, so that you can monitor the steaming process.
Cook over low-medium heat for 12 minutes, making sure the water stays at a gentle simmer.
Place the watercress on top of mixture and sprinkle the sesame seeds and continue to cook for about 3 minutes or until the eggs are set. They should be firm but jiggly.
Carefully lift the ramekins from the pot and serve.