From bon appatit

Servings: 2 1/2 pounds
Prep time: 10 Minutes
Cook time: 10 minutes
Difficulty: Easy

2 1/2 lbs zucchini, peeled, trimmed and sliced into 1/4 inch thick pieces.
1 onion thinly sliced, or 1 tsp onion powder
2 TBS kosher salt
2 cups vinegar, preferably Champagne, but white works
1 cup sugar
1/2 tsp ground ginger
1/4 tsp ground turmeric
1/4 tsp mustard seeds, or 1/2 tsp ground mustard

Toss the zucchini, onion and salt in a large colander, place in sink and let drain for two hours.
Rinse vegetables and let drain. Transfer to towels and press to squeeze moisture from zucchini.
Place in a large bowl.
Bring the vinegar and remaining ingredients to a boil in a small saucepan, stirring to dissolve sugar.
Reduce heat to medium and simmer for ten minutes.
Pour vinegar mixture over zucchini mixture and push zucchini down to coat.
Let cool to room temperature.
Cover and refrigerate overnight.
Can be made one week ahead. Keep chilled.