Method

Using a small cookie cutter, make nine discs of sourdough and toast lightly.
To make the hollandaise, place the egg yolk, white wine vinegar and Dijon mustard into a heatproof bowl over a pan of simmering water. Carefully whisk the egg over a low heat until it begins to thicken, then remove from the heat and slowly pour in the butter, whisking constantly. Give a little squeeze of lemon and season with a pinch of salt.
Using the same pan of boiling water, add a dash of vinegar and prepare the quail eggs by breaking 3 at a time into a separate bowl. Create a whirlpool in the water and gently pour in the quail eggs. Cook for approximately 90 seconds, until the whites have turned opaque. Gently remove with a slotted spoon and carefully trim away the excess whites from the yolks. Repeat with the remaining quail eggs.
To assemble the canapés, top each piece of toasted sourdough with a pinch of ham hock, a poached quail egg and a spoonful of Dijon hollandaise. Top with cress and serve immediately.