This is a lovely, spicy, warm flavored sauce that can be adapted by adding other ingredients. I often stir in hard-boiled eggs or bread crumbs soaked in vinegar, which adds different textures.
Serve with fish, cooked meats, cheese and salads.
Put the mustard leaves and garlic into a food processor and blend with 2 tsp vinegar. With the processor still running, add the olive oil in a slow stream, season to taste, then add the remaining vinegar if required.
Reprinted with permission from Jekka's Herb Cookbook by Jekka McVicar, Firefly Books 2012.
Jeremy Bailenson, founding director of Stanford University's Virtual Human Interaction Lab, is studying whether the experience of being a virtual cow will make people feel more empathy. "[Our previous work] showed that if you had occupied the avatar of another person, you showed empathy toward them," Bailenson says. "But no one had ever tried this with another species."