1 Rinse Romanesco, trim and cut into small florets. Rinse carrots, trim, peel and cut into quarters lengthwise.
2 Bring salted water to a boil in a pot. Add Romanesco and carrots and parboil until al dente, about 5 minutes. Drain well in a sieve.
3 Cut limes in half and squeeze. Mix lime juice in a large bowl with honey, season with salt and whisk in the carrot juice. Whisk in walnut oil.
4 Stir in the drained vegetables, cover with plastic wrap and marinate at least 15 minutes, stirring often.
5 Meanwhile, clean the mushrooms carefully, trim and slice on a mandoline into thin slices.
6 Trim mache, rinse, spin dry and spread on 4 plates.
7 Rinse the parsley, shake dry, pluck off the leaves and chop finely. Arrange marinated vegetables on the mache, top with porcini mushrooms and sprinkle with parsley.