How to Make It
Bring a medium saucepan of salted water to a boil. Add the turnips and boil over moderate heat until just tender, about 5 minutes. Using a slotted spoon, transfer the turnips to a platter. Repeat with the carrots, cooking them for 3 minutes, and then the onions, cooking them for 2 minutes. Refrigerate the vegetables until chilled. Halve the turnips and thickly slice the onions.
In a small bowl, whisk the olive oil with the vinegar, walnut oil and mustard and season with salt and pepper.
In a large salad bowl, toss the Bibb lettuce with the spinach, bok choy, cucumbers, basil, chervil sprigs and the cooked vegetables. Add the vinaigrette, toss to coat and serve.