Even though the "cru" in crudités means raw, in France (where they pronounce it croo-di-tay), many dipping vegetables benefit from a bit of cooking. Although there's fish sauce in the dip, you can leave it out, though then you will be missing what our friend Pengyew calls "a little something funky." Nobody will notice it, I swear. So, here's a way to start the meal on a lovely, light note; a way to be sure that you won't be stuffed before you even begin; a way to get a few veggies into your kids nice and early, while they're hungrily milling around; and a way to forget about serving salad with dinner because you're going to forget about serving it anyways.
All the veggies can be prepped, then wrapped with their own kind in paper towels or clean dishtowels and stored all together in a big Ziploc in the fridge until you're ready to arrange them on a platter.
Green beans: Snap off the stem ends, then drop them in a large pot of boiling water (steam them if you prefer), scoop them out after a few minutes, when they're just tender and bright green, and rinse them well in cold water before wrapping them up in a dishtowel to dry. Leave the water boiling for the broccoli.
Broccoli: Cut off the big stem, peel it, and slice it into narrow sticks. Cut the rest into elegant florets. Blanch it all in the boiling bean water for 2-3 minutes until just crisp-tender and bright green, then drain, chill, and wrap as for the beans.
Fennel: Trim off the feathery top, any depressed-looking outer leaves, and the very bottom, then cut the bulb into vertical slices and cut each of these in half. The core will keep the slices largely intact. Toss them with a bit of olive oil and salt, then roast these on a foil-lined baking sheet at 450 for around 10 minutes until they're browning and tender.
Brussels sprouts: Same as the fennel, trim them, cut them in half, toss with oil and salt, and roast alongside the fennel, on the same sheet even (cauliflower is also excellent this way too). Celery is simply cut into sticks; radishes are washed and trimmed; cucumbers are cut into wedges or slices; endive is separated into leaves that will be eaten only by me.
Now make the dip: wash the parsley in a large sink of water, spin it dry, then pull the leaves from their stems, without deranging yourself over the smaller stems, which are fine to include; this is a wonderful job for a seated child or an adult with a glass of wine.
In a food processor, whir together the parsley leaves, vinegar, olive oil, garlic, salt, capers, fish sauce, black pepper, and 1/4 cup of the mayo. Stop the motor to scrape down the sides every now and then, and when it's quite finely ground together, add the rest of the mayo and process until smooth and green.
Taste the dip for seasoning. It should be quite tangy and salty, so add more salt or vinegar (or fish sauce, shhh) as needed, then scrape it into a small bowl, cover, and chill until you're ready to eat it.