In a medium saucepan, bring vinegar, water, salt, sugar and lemon zest to a boil. Simmer, stirring occasionally, until sugar and salt are dissolved. Cool to room temperature.

Pierce each tomato once or twice with a wooden toothpick. Divide tomatoes, dill, garlic, red pepper and mustard seeds evenly among sterilized jars.

Pour cooled vinegar mixture into jars, leaving on inch of space at the top. Cover and refrigerate for up to one month.