# Slaw and Order: The Gratin Files

Baked Coleslaw and Red Onion Casserole with a Creamy Mayo-Sour Cream Crown

This side brings classic American slaw flavors into baked-casserole territory, proving that coleslaw mix's destiny isn't limited to backyard cookouts. You'll learn how a sweet-savory glaze and a tangy, creamy cap can transform humble veggies into a bubbling, irresistible gratin.

- Serves: 4
- Cook time: 40 minutes
- Cuisine: American
- Meal: Side
- Dietary: Vegetarian, Nut-free, Shellfish-free
- Canonical: https://cookwithherb.com/r/baked-coleslaw-and-red-onion-casserole-with-a-creamy-mayo-sour-cream-cro-a3c6a345
- Image: /api/recipes/image-file?pathname=recipes%2Fa3c6a345-7b54-4bc7-8e81-537cee7efe92-1792942419510.png

## Ingredients

- 2 tbsp unsalted butter
- 1 medium red onion, thinly sliced
- 12 oz coleslaw mix (shredded cabbage and carrots)
- 1/2 tsp kosher salt
- 1/4 tsp freshly ground black pepper
- 2 tbsp soy sauce
- 3 tbsp light brown sugar, packed
- 1 tbsp apple cider vinegar
- 1/2 cup Duke's mayonnaise
- 1/2 cup sour cream
- 1 tsp Dijon mustard
- 1/3 cup panko breadcrumbs
- 1 tbsp olive oil

## Instructions

1. Preheat your oven to 400°F. Grease an 8x8-inch baking dish with a bit of butter or nonstick spray.
2. Melt the unsalted butter in a large skillet over medium heat. Add the thinly sliced red onion and cook, stirring, until just softened, about 3 minutes.
3. Add the coleslaw mix to the skillet with the red onion, season with kosher salt and black pepper, and cook, stirring frequently, until slightly wilted but still crisp, about 4 minutes. (Herb says: Wilting the mix tames raw cabbage bite and helps prevent a soggy gratin.)
4. Pour in the soy sauce and sprinkle over the brown sugar. Stir and cook until the sugar dissolves and a glaze starts to coat the veggies, about 2 minutes.
5. Remove from heat and stir in the apple cider vinegar. (Herb says: Vinegar goes in off-heat to keep its punchy tang , heat kills acid faster than optimism at a Monday staff meeting.)
6. Spread the glazed cabbage and onion mixture evenly in the prepared baking dish.
7. In a medium bowl, whisk together Duke's mayonnaise, sour cream, and Dijon mustard until smooth. Gently spread this mixture over the top of the vegetables, all the way to the edges to seal.
8. Toss the panko breadcrumbs with olive oil in a small bowl until crumbs are evenly coated. Sprinkle the mixture over the creamy layer on the casserole.
9. Bake, uncovered, in the preheated oven until the top is golden brown and the edges are bubbling, 20 to 25 minutes.
10. Let the gratin rest for 10 minutes before serving; this helps the layers set and makes for neater squares. (Herb says: Resting isn't just for brisket. Give your casserole a breather and your plating will thank you.)