A dry, smooth chardonnay is an ideal pairing for this creamy soup.
Peel potatoes and cut into 2 cm/1 in. cubes. Chop onion and cut florets from cauliflower head. Halve bacon strips.
Preheat oven to 200°C/400°F. Heat a large pot over medium-high heat. Add butter, then add the onions and cook until translucent and fragrant, approx. 1 min. Add potatoes and fry for approx. 2 min., then add vegetable broth. Lower heat and simmer for approx. 25 min.
Meanwhile, line a baking sheet with parchment paper. Spread cauliflower florets evenly over baking sheet, drizzle with olive oil, and season with salt and pepper to taste. Bake at 200°C/400°F for approx. 12 min. Set aside.
Fry bacon over medium heat until crispy. Transfer to a paper towel-lined plate to drain.
In a mixing bowl, mix sour cream with horseradish until combined.
Add horseradish mixture to the potatoes, then remove pot from heat. Use a hand blender to purée until smooth.
Transfer soup to a serving bowl and garnish with roasted cauliflower, bacon, and parsley. Season to taste with salt and pepper. Enjoy!