In large saucepan, heat grapeseed oil over medium-high heat. Add onion and sauté, stirring often, until softened and translucent, about 4 minutes. Stir in garlic and cook until fragrant, about 1 minute. Stir in cabbage, potato, apples, vinegar, vegetable stock, and salt. Bring mixture to a simmer, lower heat to medium-low, cover, and let slowly simmer until cabbage is tender, about 15 minutes.

Working in batches, if necessary, in blender, purée soup until very smooth. Return back to saucepan and warm over medium heat. Taste and adjust seasoning, as desired.

To serve, divide soup among 4 serving bowls. Swirl 1 Tbsp sour cream into each bowl of soup and top with a sprinkle of shredded raw cabbage. Enjoy while warm.