Let cheese stand at room temperature for 30 minutes. In a small bowl stir together tomatoes, rosemary, lemon zest, and garlic. Shape cheese into twelve 3/4-inch balls; roll in tomato-herb mixture. Place on plate; cover and chill up to 24 hours. To serve, place each cheese ball in a nasturtium blossom. Drizzle cheese with a small amount of olive oil, avoiding the flower.