1) Keep a cheese cloth or a coffee filter over a strainer.
2) Place it over a bowl.
3) Fill yogurt into it and allow to drain for 30 minutes.
4) Pour it in a medium bowl.
5) Add celery, almonds, oil, lemon juice, garlic, and thyme.
6) With a melon scoop or small spoon, scoop out the centers from the beets, leaving a 1/4-inch shell.
7) Reserve the shells.
8) Deice the scooped part of the beets.
9) Combine to the yogurt mixture.
10) Fill the mixture into the beet shells.