Rinse tomatoes. Cut in half lengthwise and scoop out seeds. Lay on paper towel to soak up any extra liquid.
Finely chop olives. Beat cream cheese. Add sour cream or yogurt. Stir in olives and a pinch of salt and pepper. If desired, reserve a few small pieces of olive to press into top after stuffing.
Using a tiny spoon, press cream cheese mixture into tomatoes.
Sprinkle fresh chives over top to garnish.
Refrigerate before serving to allow cream cheese to set if getting soft.