Rinse the anchovies and place in a bowl. Trim, wash and spin-dry the lettuce leaves and place to one side.
Bring a couple of large pans of water to the boil. Wash the beetroots, reserve a couple, then pop the rest into one of the pans. Boil for 10 minutes, or until tender, then finely slice the reserved beetroots on a mandolin (use the guard!).
Make the dressing by whisking the oil, vinegar, mustard and capers together, then season with sea salt and black pepper.
Drain the beetroots in a colander and leave to steam dry. When cool enough to handle, carefully peel away the skins (you might want to wear gloves!). Slice any larger beetroots in half.
Transfer the beetroots to a bowl and drizzle over half the dressing, toss to coat and leave to one side.
Trim the French beans. In the other pan, add the quail eggs and French beans, simmer for 3 to 4 minutes, then drain. Carefully peel the eggs, then slice in half.
Pick and finely chop most of the herbs, add to the leftover dressing, then tip into a salad bowl.
Halve the tomatoes, layer up in the salad bowl with the lettuce and anchovies, then drizzle over the dressing.
Gently tumble in the cooked and raw beetroots, the eggs and green beans, then scatter over the remaining herbs. Quickly toss together, and serve with warm sliced sourdough bread, if you like.