Bánh flan — Vietnamese steamed caramel custard

Set out six clean ramekins and a lidded steamer rack. Keep the eggs and milk refrigerated until preparation. Measure the boiling water and place it beside the stove for the caramel.

Put the sugar and 30 ml water in a small heavy saucepan. Heat over medium without stirring, swirling the pan gently as the syrup bubbles and turns deep amber. Remove from the heat and carefully add 15 ml boiling water, standing back because it can spit. Swirl, then quickly divide the caramel among the ramekins and tilt each to coat the base. Let it set.

Warm the whole milk and condensed milk in a saucepan over low heat, stirring, until smooth and hot but not boiling. Remove from the heat, stir in vanilla and cool for 5 minutes.

Gently whisk the eggs with the salt just until combined; do not foam them. Slowly pour in the warm milk mixture while stirring gently. Strain the custard twice through a fine sieve into a pouring jug to remove egg strands and bubbles.

Divide the custard among the caramel-lined ramekins and cover each with foil or a lid. Set them in a steamer above gently simmering water, with the water below the ramekin rims. Cover and steam over low heat for about 25–35 minutes, until just set with a slight central wobble. Check the centre of a custard with a clean thermometer; egg dishes must reach 71°C / 160°F. Continue steaming in 3-minute increments if needed.

Carefully remove the ramekins. Cool at room temperature for no more than 30 minutes, then cover and refrigerate at or below 4°C / 40°F for at least 4 hours until fully chilled. Keep them refrigerated during the remaining chill time.

To serve, run a thin knife around each edge and invert onto a small plate; let the caramel flow over the custard. If desired, pour about 10 ml cooled strong Vietnamese coffee over each portion and add a little crushed ice.