Wedges of large green tomatoes and whole small tomatoes both make delicious pickles. Kept in sealed canning jars, their flavor will continue to develop over several months.
In a large bowl, combine onion, bell pepper, and tomatoes. Pack mixture into 3 one-quart or 6 one-pint canning jars. Place a garlic clove and a red chile in each jar, and set aside.
In a large saucepan, combine sugar, salt, vinegar, mustard seeds, cloves, celery seeds, and allspice. Bring to a boil over medium-high heat; stir until sugar dissolves. Pour mixture over produce, leaving a 1/2-inch space at the top of each jar. Wipe rims of excess; screw on lids.
Bring a large stockpot of water to a boil. Using canning tongs, gently place jars in boiling water, making sure the water covers the jars (if not, add additional water to cover). Let jars sit in gently simmering water for 10 minutes. Remove; let cool slightly. Check seal by pressing in center of lid. If it doesn't pop back, it is properly sealed. If it does, return jars to water for 10 more minutes. Let sealed jars cool completely.
Let pickled tomatoes stand until flavors have melded, at least 2 weeks.
Store unopened jars in a cool, dark place up to 6 months. Once opened, jars will keep in the refrigerator up to 1 month.