Potato & Tomato Gratin

“Let’s build a fire!” I said to B the other day, as I threw on a heavy sweatshirt. The tip of my nose was cold and I already had wool socks on my feet.

“But it’s not fire season yet — it’s only the beginning of September,” he replied.

“Well, September or not,” I countered, “it’s fifty degrees with rain and howling wind — perfect fire weather to me…besides, I’m freezing!” B looked at me, chuckled, and pulled on his boots to grab some firewood outside.

I don’t know why, but every September it takes me by surprise when crisp, crackly, cool Fall shows up on our doorstep, knocking loudly. And I don’t mind at all — I love pulling out my sweaters and earth-toned fall clothes, sleeping with a few extra blankets and waking up to crisp blue skies and fog-hugged hills.

My only regret — which is really a moot point since I’ve frozen bags upon bags of them in our chest freezer — is that blueberry season is over. However, no one is as sorry as our daughter A, who is a true blueberry monster:

September is sometimes a slightly discombobulating time at the farmer’s market for me. Often I’m pulling on a fleece jacket and debating whether or not to wear fingerless-gloves for a little extra warmth on my open-air shopping trip, but then the market stall shelves are brimming with produce that I associate more with the peak of summer — luscious ripe tomatoes, cucumbers, eggplants, peppers. I have to keep reminding myself that in our Zone 5 climate,  September and early October seem to really be our peak.

late summer/early fall potatoes, tomatoes & thyme

But this recent spate of cool weather is a nice excuse to turn on the oven again; my motivation to bake skyrockets and all I crave are warm roasted things, soups, casseroles, and this year, gratins.

sweet, toffee-colored caramelized onions

A recent addition to my cookbook collection is Sunday Supper at Lucques by Suzanne Goin, which — if you don’t already have it — I’m recommending to all my friends who love to cook. I’ve spent many a dreamy weekend afternoon while the baby sleeps thumbing through her seasonal menus and dreaming of how the dishes must taste. I made her fresh corn soup over the summer (oops – time came and went and that never made it to the blog), and top on my list to try when fall arrived was this potato and tomato gratin.

thinly sliced potatoes tossed with cream, salt and thyme

luscious, drippingly ripe tomatoes waiting to be tucked into the gratin

For this gratin, potatoes and tomatoes are thinly sliced and seasoned with cream and thyme, then tucked into layers with golden-brown caramelized onions.

layering, layering

make the top presentation pretty!

After a showering of basil over the top, the gratin is baked until the potatoes are tender and tomatoes exude their juices and melt into the dish. The entire dish is wonderfully seasoned and a pitch-perfect bridge from summer to fall.

A few recipe notes:

• Goin is very precise with measurements for seasoning with salt and pepper throughout each recipe in her book. As someone who tries to accurately season (but sometimes can overseason things in my paranoia about making things underseasoned), I find this helpful.
• It takes almost 3 hours start to finish when you factor in a 2+ hour bake time. Which, I think, makes it a great recipe for a weekend afternoon, but probably not a good weeknight side dish. The dish is marvelous, though, so don’t let the 2-hour bake time deter you. Just don’t plan to make this on a Thursday night like I initially did. 🙂

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From Sunday Suppers at Lucques by Suzanne Goin

Ingredients
5 tablespoons extra-virgin olive oil
6 cups thinly sliced onions (about 1 1/2 pounds)
1 tablespoon thyme leaves, divided
1 tablespoon unsalted butter
1 1/4 pound Yukon Gold potatoes, peeled (note: I did not peel mine)
1/2 cup heavy cream
2 1/4 pound ripe tomatoes (I used a mix of red and green tomatoes)
1/4 cup sliced basil
kosher salt and freshly ground black pepper

Directions

Heat a large saute pan or Dutch oven over high heat until hot, then add 3 tablespoons olive oil, the onions, 1 teaspoon thyme, 1 teaspoon salt, and some pepper. Cook for 6 minutes, stirring often, then turn down the heat to medium and add the butter. Cook an additional 10-15 minutes, scraping with a spoon or spatula until the onions start to caramelize. Turn the heat down to low and continue cooking until the onions are a deep golden brown, another 5-10 minutes. Turn the heat off and set aside.

Preheat the oven to 350 degrees F.

Thinly slice the potatoes (using a mandoline or a sharp chef’s knife) into 1/8-inch-thick rounds. Toss them in a bowl with the cream, 1 teaspoon thyme, 1 teaspoon salt, and some freshly ground black pepper.

Slice the tomatoes into 1/4-inch thick slices, arrange them on a plate and season with 1 teaspoon salt and some pepper.

To layer the gratin, first spread half the caramelized onions in an even layer in a 9×9 inch gratin or baking dish. Top the onions with one layer of alternating potatoes and tomatoes (using about half of each), then drizzle with 2 tablespoons cream (from the potato bowl) and 1 tablespoon olive oil. Season with 1/4 teaspoon salt, a healthy pinch of black pepper, 1/2 teaspoon thyme and half the basil.

Repeat the layers, making the top potato/tomato layer pretty since this is the top presentation layer of the gratin. Pour the remaining cream (from the potato bowl) and remaining tablespoon olive oil over the gratin and season with 1/4 salt, a pinch of pepper, the remaining 1/4 teaspoon thyme and the remaining basil. Press all the vegetables down with your fingers; the cream will come up through the layers and coat the vegetables evenly.

Cover the baking dish tightly with aluminum foil and bake for 1 1/2 to 2 hours, until the potatoes are tender when pierced. Turn the oven temperature up to 450 degrees F, uncover the gratin, and bake an additional 25-30 minutes until the top is bubbly and golden brown. Let cool slightly before serving.