Chop your grated horseradish into tiny pieces. Add to a medium mixing bowl.
2 tablespoon grated horseradish
Add the Greek yogurt, sour cream, salt, and pepper to the mixing bowl.
1/4 cup plain Greek yogurt, 1/4 cup lite sour cream, 1/4 teaspoon salt, 1/8 teaspoon black pepper
Grate the garlic clove into the bowl of ingredients. Add the lemon juice.
1 clove garlic, 2 teaspoon lemon juice
Whisk the whole sauce together well. Taste it and add more horseradish, salt, or pepper to suit your tastes. Top with the sliced green onion tops.
2 tablespoon sliced green onion tops
Notes
Make sure you find regular grated horseradish, not a pre-prepared horseradish sauce. You can usually find this in the deli section of most large grocery stores.