Heat oil in a dutch oven over medium heat. Add chopped onion and 1 teaspoon of sea salt. Saute the onions until they're translucent (5 minutes). Next, add the garlic. Stir for one minute. –
Then add the celery, carrots, bay leaf and oregano. Saute, stiring occasionally for 10 minutes.
Add the split peas, water and another teaspoon of sea salt. Bring to a boil and let simmer for 45 minutes with the lid slightly ajar. During the last five minutes of cooking, stir in the parsley.
Once the split peas are fully cooked, turn off the heat. Transfer 2 cups of the soup to a high speed blender. Emulsify and add the pureed soup back into the pot. Stir in apple cider vinegar and season with pepper.