In a large pot, heat the extra-virgin olive oil over medium heat. Add the diced yellow onion and cook for about 3 minutes, or until translucent.

Stir in the minced garlic, dried thyme, and fine sea salt, cooking until fragrant for about 1 minute.

Pour in the vegetable broth and add the grated potato. Bring the mixture to a boil with the lid slightly ajar for about 10 minutes, until the potato becomes soft.

Incorporate the frozen peas and cook them until they turn bright green, about 2-3 minutes. If using, stir in the baby spinach until it wilts.

Use an immersion blender to puree the soup until smooth. Alternatively, blend in batches in a standard blender. Season with black pepper and adjust salt to taste.