- Combine vegetables.
- Stir together the mayonnaise, sour cream, onion, lemon juice, Worcestershire, and white pepper.
- Add to vegetables; stir gently to combine.
- Chill at least 1 hour.
- Cut a small slice from the top of each tomato.
- Scoop out seeds, leaving a 1/2" shell.
- Sprinkle cups lightly with salt.
- Invert tomatoes, cover and chill until ready to serve.
- To serve, spoon vegetable mixture into shells.