Ingredients

• 1 ¹⁄₂ lb. green tomatoes, cored and finely chopped
• 1 medium yellow onion, finely chopped
• 1 rib celery, finely chopped
• ¹⁄₂ green bell pepper, cored, seeded, and finely chopped
• ¹⁄₂ red bell pepper, cored, seeded, and finely chopped
• 2 tbsp. kosher salt
• ¹⁄₂ cup sugar
• ¹⁄₃ cup distilled white vinegar
• 1 ¹⁄₂ tsp. dry mustard
• 1 ¹⁄₂ tsp. yellow mustard seeds
• 1 tsp. celery seeds
• 1 tsp. crushed red chile flakes
• ¹⁄₄ tsp. ground coriander

Instructions

1. Toss tomatoes, onions, celery, and peppers in a large bowl with salt; cover with plastic wrap and let sit at room temperature for 4 hours or overnight. Transfer vegetables to a sieve and press to extract excess juices; discard juices.
2. Transfer vegetables to a 6-qt. saucepan and add remaining ingredients. Cover, bring mixture to a boil, reduce heat to medium-low, and simmer, stirring occasionally, until vegetables are very soft, about 2½ hours. Transfer relish to a jar and let cool. Cover and refrigerate for up to 2 weeks.