• 1/2 tsp. ground turmeric
• 1/2 tsp. ground black pepper
Cut the zucchini lengthwise into thin strips using a julienne peeler or a mandoline. Cut the strips crosswise into matchsticks. Transfer to a large nonreactive bowl. Add the onion, bell pepper and salt. Toss to combine. Cover; let stand at room temperature 6 hours or up to 1 day.
Drain the zucchini mixture in a large colander. Rinse thoroughly; drain again. Transfer to a large nonreactive saucepan. Add the sugar, vinegar, water, celery seeds, nutmeg, turmeric and pepper. Stir to combine. Heat to a boil over high heat; reduce the heat to medium-low. Simmer, stirring occasionally, until slightly thickened, 25 to 30 minutes.
Have ready hot, sterilized jars and their lids. Ladle the hot relish into the jars, leaving 1/4 -inch of space at the top. Remove any air bubbles. Wipe the rims clean; seal tightly with the lids. Process the jars in a boiling water bath 10 minutes. Cool jars; test seals. Store. If the seal has failed during processing, refrigerate the jar up to 1 month.