Grilled Cauliflower ‘Steaks’ with Tonnato Sauce and Walnut Salsa

This was a light dinner; would be good as a starter, as Ottolenghi suggests. DH thought the tastes of the tonnato sauce (the bottom layer) and the salsa conflicted; I thought they were fine together. He also said he'd like the salsa in/on an omelet or scrambled eggs.

Unfortunately my fresh parsley was way past its use-by date and there was none in the freezer, so I had to use the dried stuff.

Ottolenghi has you cut only two "steaks" from the center of each cauliflower, which could waste quite a bit of cauli if you're not prepared to use the rest, but the steaks hold together well because they both have a substantial portion of the central stem.