1. Trim off and discard stem ends from brussels sprouts; rinse sprouts.
2. In a 10- to 12-inch frying pan, combine olive oil and 3/4 cup water; bring to a boil over high heat. Add sprouts, cover, reduce heat to medium, and shake pan occasionally until sprouts are tender when pierced, 8 to 14 minutes. Uncover and stir in tomatoes and vinegar.
3. Pour into a bowl and add salt and pepper to taste.