01 - Preheat oven to 400°F.
02 - Arrange cauliflower florets, sliced zucchini, and diced red bell pepper on a baking sheet. Drizzle with olive oil, season with salt and pepper, and toss to coat evenly.
03 - Roast vegetables for 25 to 30 minutes, stirring halfway through, until tender and golden brown.
04 - While vegetables roast, cook bacon strips in a skillet over medium heat until crispy. Drain on paper towels and chop into bite-sized pieces.
05 - In a small bowl, whisk together mayonnaise, sour cream, Dijon mustard, lemon juice, salt, and pepper until smooth.
06 - In a large bowl, combine roasted vegetables, baby spinach leaves, and chopped bacon. Add the dressing and toss gently to coat all ingredients evenly.
07 - Divide salad among plates and garnish with toasted walnuts and freshly chopped chives. Serve warm.