Corned Beef and Tomato Hash Bake

3 cups finely diced cooked corned beef
2 cups peeled and diced potatoes, cooked in water to cover until tender and drained
1/4 cup (1/2 stick) butter
1 medium-size onion, finely chopped
1/2 small green bell pepper, seeded and finely chopped
1 garlic clove, minced
1 tablespoon finely chopped fresh basil leaves or 1/2 teaspoon dried
1/2 cup milk
Salt and black pepper to taste
2 medium-size ripe tomatoes, cut into 1/2 inch thick slices
Dijon mustard as needed
1/2 cup dry bread crumbs
2 tablespoons butter, melted

1. Preheat the oven to 350 degrees. Butter a 2-quart casserole and set aside.

2. In a large mixing bowl, combine the corned beef and potatoes, toss, and set aside.

3. In a medium-size skillet, melt the butter over moderate heat, add the onion, bell pepper, garlic, and basil, stir for 3 minutes, add to the corned beef and potatoes, and mix well. Add the milk, season with salt and pepper, mix well, and scrape the mixture into a prepared casserole. Spread the top of each tomato slice with mustard and arrange the slices evenly over the casserole.

4. In a small mixing bowl, combine the bread crumbs and melted butter, mix well, spoon evenly over the tomatoes, and bake till lightly browned, about 30 minutes.