Remove the leaves and stalk from the cauliflower, divide into florets and wash. Bring plenty of salted water with vinegar to the boil in a large saucepan, add the florets and cook for about 8 minutes until crisp.
Then drain, quench and drain everything. Chop into bite-sized pieces and transfer to a large bowl. Finely dice the garlic and onion, wash the sorrel. Drain everything or spin dry. Cut the leaves into fine strips and add to the cauliflower.
For the salad dressing, whisk together lemon juice, sour cream and walnut oil. Season with salt and pepper, add onion and garlic cubes and mix in. Add the salad dressing, mix well and let steep for 30 minutes.