1/2 cup loosely packed flat-leaf parsley leaves, plus extra to serve
Baby red vein sorrel leaves, to serve
2 egg yolks, at room temperature
11/2 tbs Dijon mustard
2 tsp lemon juice
3/4 cup (180ml) grapeseed oil
For the mayonnaise, place the egg yolks, mustard and lemon juice in a food processor and whiz to combine. With the motor running, gradually add the oil until combined.
Add a little warm water, 1 tsp at a time, if mayonnaise is too thick. Season to taste and set aside until ready to use.
Place the potatoes in a large saucepan of lightly salted water, bring to the boil over a high heat, then reduce heat to medium and simmer for 20-25 minutes or until potatoes are tender but still firm and not falling apart.
Drain. When cool enough to handle, slice into 1cm-thick rounds.
Meanwhile, place the eggs in a small saucepan, cover with cold water and bring to the boil over a medium heat. Cook for 6 minutes from the boil for soft-boiled, or adjust time to cook to your liking.
Drain and refresh in cold water, then carefully peel the eggs and cut into halves. Set aside.
Place the potato, egg, tomato, ham and cornichon in a large bowl, and gently toss to combine. Add parsley and enough mayonnaise to just coat the salad ingredients. Season to taste and toss gently to combine. Scatter with extra parsley and baby sorrel leaves. Serve immediately