Special equipment: eight 4-ounce ramekins arranged, with some distance between each, in a water bath.
Preheat the oven to 325 degrees F.
In a medium saucepan, stir together the condensed milk, 1 1/2 cups water and the salt. Bring to a simmer and cook until the ingredients are fully integrated, 5 to 8 minutes. Remove from the heat. Add the citrus zests and allow to cool.
In a medium bowl, whisk together the egg yolks, eggs and vanilla. Pour the condensed milk mixture over the eggs and whisk to blend.
Fill the ramekins about three-quarters each with the liquid and place the water bath in the center of the oven. Bake until they are almost firm in the center when lightly shaken, 45 to 50 minutes. Refrigerate until cooled.
Serve the ramekins topped with slices of fresh orange and lemon, or by themselves with some cookies.
Recipe courtesy of Alex Guarnaschelli