Adapted by Ellen Touart-Grob from David Tanis
- 1 pound zucchini, ends trimmed
- 1 small yellow onion, peeled
- 2 generous tablespoons kosher salt
- Ice water and ice cubes
- 2 cups apple-cider vinegar
- ¾ cup maple syrup or 1 cup sugar
- 1 ½ teaspoons dry mustard
- 1 ½ teaspoons yellow or brown mustard seeds, or a combination
- 1 teaspoon turmeric
With a mandolin or sharp vegetable peeler, cut zucchini lengthwise into 1/16-inch slices. Cut onion from the top to root, the same thickness.
Place the zucchini and onion in a low wide (non-reactive) bowl, toss with salt and cover with ice water. Add a few ice cubes. Leave for 1 hour, until faintly salty and slightly softened when tasted. Drain, discard ice and dry vegetables thoroughly between kitchen towels. Rinse and dry bowl.
Make the brine: Combine vinegar, maple syrup or sugar, dry mustard, mustard seeds and turmeric in a nonreactive saucepan, and simmer over medium-high heat for about 3 minutes. Turn off heat and set aside until just warm to the touch.
Return zucchini to the bowl and pour cooled brine over, then stir to distribute spices.
Transfer mixture and brine to pint jars and refrigerate for at least a day before serving.