RED POTATO & TOMATO GRATIS

I wanted to make something using Leeks. It was the first time for me using leeks. So I searched around for a nice recipe with leeks and found this French recipe which has been a hit at our house. This also a perfect thing to serve to guests.

Ingredients:
For Leeks -
1 tbs olive oil
3 cups sliced leeks (white and pale green parts), washed thoroughly

For potatoes -
1 lb red potatoes, unpeeled, cut into 1/4 inch slices
1/2 tsp salt; more for boiling the potatoes
1 1/2 tbs olive oil
2 tsp chopped rosemary (can also use 1/2 tsp dried rosemary)

To assemble the gratin -
1 tsp chopped fresh rosemary (or a pinch of dried rosemary)
1 1/4 lb ripe tomatoes. cored and cut into 1/4 inch slices
1 3/4 cup grated Gruyere cheese (can use any Swiss cheese)
1 tsp salt
ground black pepper to taste
1 1/2 tbs olive oil
2/3 cup breadcrumbs mixed with 2 tsp olive oil

Preparation:
The leeks -

• Heat oil in medium skillet over medium heat.
• Add leeks and saute, stirring frequently until limp and lightly browned - about 15 minutes.
• Spread the leeks evenly in the bottom of an oiled 2 quart shallow gratin dish (or baking dish), preferably oval. Let it cool.

The potatoes - 

• In a medium saucepan, cover the potato slices with well-salted water and bring to a boil.
• Reduce the heat to a gentle boil and cook for 5 minutes or until the potatoes are just barely tender.
• Drain and rinse under cold water until cool.
• Pat dry. Toss the potatoes with salt, olive oil and rosemary.

Assemble the gratin -

• Heat oven to 375F.
• Sprinkle 1/2 tsp of chopped rosemary over the leeks
• Starting at one end of the baking dish, lay a row of slightly overlapping tomato slices across the width of the dish.
• Prop the tomatoes against the dish at a 60 degree angle.
• Cover the row of tomatoes with a generous sprinkling of cheese.
• Arrange a row of potato slices over the tomatoes.
• Sprinkle again with cheese.
• Repeat with alternating rows of tomatoes and potatoes, sprinkling each with cheese until the gratin is full.
• Sprinkle about 1/2 tsp salt and the remaining rosemary and season with pepper.
• Drizzle with olive oil.
• Mix any remaining cheese with the breadcrumb mixture and spread this over the while gratin. 
• Cook until gratin is well-browned all over and the juices have bubbled for a while and reduced considerable - about 60 minutes.
• Cool it for a bit before serving.