Green Tomato Piccalilli

About the recipe
Piccalilli is an English relish-like condiment with a dominant mustard flavor. Substituting green tomatoes gives it a Southern flair.
Piccalilli is perfect for canning and gift-giving. To can the piccalilli for long-term storage, transfer the hot relish to sanitized half-pint- or pint-sized canning jars and process in a boiling water bath for 5 minutes.
Serves: 2 cups
Hands On Time: 30 minutes
Total Time: 1 hour and 30 minutes
Ingredients
1 1/4 pounds green tomatoes, cores removed and cut into 1/2 inch pieces
2 tablespoons kosher salt
1/2 cup apple cider vinegar
1/4 cup sugar
1/4 cup yellow mustard
1 tablespoon mustard seeds
1 clove garlic, minced
1/2 teaspoon freshly ground black pepper
1/4 teaspoon red pepper flakes
Instructions
In a large bowl, toss the green tomatoes with 1 tablespoon of the salt, transfer to a colander, and let sit for 1 hour.
Rinse off the salt with cold water and drain well.
In a large saucepan, combine the remaining 1 tablespoon salt with the vinegar, sugar, yellow mustard, mustard seeds, garlic, pepper and red pepper flakes. Bring to a simmer over medium-high heat.
Add the drained tomatoes and return the liquid to a low simmer. Reduce the heat to medium-low and cook, stirring occasionally to prevent scorching, until mixture has thickened, 15 to 20 minutes. Let cool to room temperature before transferring to storage containers. Refrigerate if not canning (see note).