Add salt and 2 tablespoons lemon juice to a large pot of water and bring to a boil. Add the whole cauliflower and cook for 30 minutes until tender. Drain well and set aside.
Cut the 2 red peppers, 1 onion, and 1 small green pepper into small cubes. Heat the vegetable oil in a large pan over medium heat. Add the cut vegetables and sauté for 5 minutes until softened and translucent. Remove the vegetables from the pan and set aside on a plate.
Add the tartare to the hot pan over medium heat and cook for 5 minutes, stirring frequently, until the meat is browned. Pour in the canned tomatoes, vegetable stock, and paprika powder. Reduce the heat to low and simmer for 15 minutes.
Remove the pan from heat. Stir in the sour cream until well combined. Add the cooked vegetables back to the pan and mix gently. Season with salt and pepper to taste.
Cut the cooked cauliflower into quarters. Arrange the cauliflower quarters on serving plates. Spoon the minced meat sauce over the cauliflower. Finely chop the parsley and sprinkle it over the dish as a garnish.