Smoked fish mayo, a Midwestern riff on the Italian tonnato, is a hearty sauce that enriches any plate of roasted vegetables but especially smoky, frizzle-tipped grilled asparagus.
In a food processor whiz the egg, lemon zest, juice and a big pinch of salt
While the machine is on, slowly drizzle in the oils to make a mayo
Remove the skin from the fish and add to the food processor and blend into a chunky sauce
Heat a grill to medium high heat
Dress the asparagus with a glut of olive oil, pinch of salt, and couple of grinds of black pepper
Grill the asparagus, with the stalks over the hotter part of the grill and the tips on the cooler side, until they have softened and taken on a bit of char
Transfer to a serving platter and then dot with the smoked fish mayo to serve