Prepare your vegetables by washing the yellow bell peppers, removing the seeds and membranes, and chopping them into medium-sized chunks. Dice the onion and mince the garlic.

Heat the olive oil in a large pot over medium heat. Add the chopped onions and sauté until translucent. Add the minced garlic and cook for one minute.

Add the yellow peppers and fresh thyme, stirring frequently for about five to seven minutes until the peppers soften.

Pour in the vegetable broth and bring to a gentle boil. Reduce heat and let it simmer for about twenty minutes until the peppers are tender.

Remove from heat and let cool for a few minutes. Blend the soup until smooth, passing through a fine-mesh sieve if desired.

Stir in the Greek yogurt or cream and lemon juice. Season with salt and white pepper. Refrigerate for at least four hours before serving.