Preparation Toss cubed feta, oil, shallot, and oregano in small bowl. Season with salt and pepper. Cut 12 tomatoes crosswise in half. Scoop out tomato pulp with melon baller or small spoon. Place tomatoes, cut side up, on serving plate. Sprinkle with salt and pepper. Stuff hollowed cherry tomatoes with marinated feta. Slide in olive half alongside cheese. Drizzle with additional olive oil. DO AHEAD: Can be made 6 hours ahead. Cover and chill.
Preparation Toss cubed feta, oil, shallot, and oregano in small bowl. Season with salt and pepper. Cut 12 tomatoes crosswise in half. Scoop out tomato pulp with melon baller or small spoon. Place tomatoes, cut side up, on serving plate. Sprinkle with salt and pepper. Stuff hollowed cherry tomatoes with marinated feta. Slide in olive half alongside cheese. Drizzle with additional olive oil. DO AHEAD: Can be made 6 hours ahead. Cover and chill.