Stir oil, salt, and pepper together in a large bowl. Add cauliflower slices and gently toss to coat. Carefully lay the cauliflower in a single layer on to a baking sheet and roast until tender, 10 to 12 minutes.
Top with cheese, return to the oven and roast until the cheese has melted, 1 to 2 minutes.
Top each cauliflower slice with a drizzle of sour cream and sprinkle with pork (or bacon) and scallion greens.