Heat the extra virgin olive oil in a large pot over medium heat.
Add the diced yellow onion, celery, and minced garlic to the pot and sauté for 5 minutes until the vegetables are softened and translucent.
Peel and dice the Russet potato into small, uniform cubes and add them to the pot.
Pour in the clam juice and season with dried thyme, sea salt, and black pepper.
Bring the mixture to a gentle boil, then reduce heat to low, cover, and simmer for 12-15 minutes until the potatoes are tender when pierced with a fork.
Stir in the drained chopped clams and cook for an additional 2-3 minutes to heat them through.
Remove the pot from the heat and allow it to cool slightly for one minute.
In a small bowl, whisk a few tablespoons of the warm broth into the Greek yogurt to temper it, then stir the yogurt mixture back into the main pot until the soup is creamy.
Ladle the chowder into bowls and garnish with freshly chopped parsley before serving.