1.For pasta dough, blanch parsley, dipping straight in and out of a saucepan of boiling water, and drain well but don’t refresh. Process parsley in a food processor until finely chopped, then, with motor running, add egg yolks immediately so they take up the maximum colour from the parsley. Add oil and a good pinch of fine salt, then add flour and pulse until dough starts to come together. Tip out onto a bench and knead until smooth (10-15 minutes; this can also be done in an electric mixer fitted with a dough hook). Wrap dough in plastic wrap and rest at room temperature for 20 minutes.
2.For sorrel butter, process sorrel and parsley in a food processor to finely chop, then add butter and lemon juice, season with finely ground pepper and pulse until combined. Wrap in plastic wrap, shape into a cylinder and refrigerate until required.
3.Divide pasta dough into 3 then, working with one piece at a time, roll through a pasta machine starting at widest setting, rolling and folding until smoother, then continue to roll, reducing settings notch by notch, until dough is 5mm thick. Dust pasta sheets with flour, then fold sheets over on themselves a few times and cut with a large sharp knife in a gentle sawing motion into very thin strips. Set aside on a floured tray until required.
4.Shake excess flour gently from pasta and cook in a large saucepan of boiling salted water until al dente (2-4 minutes). Drain and transfer to a serving bowl, top with slices of sorrel butter and lemon thyme leaves, toss gently to combine and dot with a few lemon thyme flowers and serve.
Duck eggs are available from Asian grocers and David Jones food halls.