Wash tomatoes and lemon under cold running water; drain. To peel tomatoes, blanch 30 to 60 seconds in boiling water. Immediately transfer to cold water. Cut off peel. Do not core tomatoes. Tie spices and fresh ginger in a spice bag.

Combine sugar, lemon slices, water and spice bag in a large, deep stainless steel saucepan. Bring to a boil over high heat, stirring to dissolve sugar. Reduce heat and boil gently, stirring occasionally, for 15 minutes.

Add tomatoes and boil gently, stirring frequently, until tomatoes are transparent. Remove from heat, cover and let stand in a cool place (70 to 75°F) for 12 to 18 hours.

Prepare boiling water canner. Heat jars in simmering water until ready for use. Do not boil. Wash lids in warm soapy water and set bands aside.

Transfer tomatoes and lemon slices to a glass or stainless steel bowl and set aside using a slotted spoon. Discard spice bag. Bring syrup to a boil over high heat, stirring constantly. Boil hard, stirring constantly, until thickened, about 3 minutes.

Add reserved tomatoes and lemons. Bring back to a boil and boil hard, stirring constantly, for 1 minute. Remove from heat and skim off foam.

Ladle hot preserves into a hot jar leaving a 1/4 inch headspace. Remove air bubbles. Wipe jar rim. Center lid on jar and apply band, adjust to fingertip tight. Place jar in boiling-water canner. Repeat until all jars are filled.

Water must cover jars by 1 inch. Adjust heat to medium-high, cover canner, and bring water to a rolling boil. Process half-pint jars 20 minutes, adjusting for altitude. Turn off heat and remove cover. Let jars cool 5 minutes. Remove jars from canner; do not retighten bands if loose. Cool 12-24 hours. Check lids for seal, they should not flex when center is pressed.