Preheat the oven to 425°F.
Add the sliced cabbage to a large sheet pan and drizzle with 2 tbsp olive oil. Season with 1 tsp salt and pepper to taste. Toss and roast for 20-25 minutes, tossing halfway, until the cabbage has crisp edges.
Pat the beans dry with a kitchen towel. Add them to a parchment lined sheet pan with 1 tbsp olive oil, ½ tsp salt, paprika and garlic powder. Toss to coat and roast for 22-27 minutes, tossing halfway, until crisp.
Remove the beans from the oven, add the walnuts and toss, then place back in the oven for 3-5 minutes.
Make the dressing by adding all dressing ingredients to a high speed blender and blend until smooth.
Assemble the salad by adding the roasted cabbage, arugula, apples and pickled onions to a bowl.
Add the desired amount of dressing and toss.
Top with the roasted white beans and walnuts before serving.
