Dice green tomatoes, onions, and bell peppers.

Combine the diced vegetables in a bowl.

Drain any excess liquid from the combined vegetables.

In a large pot, add the drained vegetables, sugar, vinegar, and celery seed.

Heat the mixture to a boil over medium-high heat.

Once boiling, reduce the heat to low and simmer for 30 minutes, stirring occasionally.

Prepare hot jars for canning.

Carefully fill the hot jars with the hot relish.

Seal the jars properly.

Allow the jars to cool completely to ensure a proper seal.

Serve with white or brown gravy, or as a condiment for other dishes.