Mary Beth Clark

Culinary Educator · Consultant · Author

Roasted Leeks, Fennel, and Tomatoes au Gratin

Roasted Leeks, Fennel, and Tomatoes au Gratin segues from end-of-summer's garden to autumn's promise of delectable dishes to be shared with friends. Begin this promise by combining the trio of leeks, fennel, and tomatoes, popular and readily available in both seasons. Roast them together until slightly caramelized and burnished on their edges. They become fork-tender and so rich in flavor. It does not take much to make a great-tasting dish, just really good produce and a light touch.

Serve this dish as an appetizer or main dish with bruschetta, perhaps accompany with an assortment of cheese. As a side dish, serve with roast chicken, grilled steak, chops, or hearty sausages, and roasted or grilled seafood. Purposely double or triple the recipe so there are leftovers. Refrigerated for even 2 or 3 days, this roasted mix is absolutely delicious stuffed into crunchy panini or draped over juicy turkey or salmon burgers. Pizza and flatbread never tasted so good as when topped with this savory treat!

Layer the ingredients and roast them in the ovenproof dish or pan in two separate stages. Begin by roasting the leeks and fennel for 20 minutes since they require more cooking time than tomatoes. Remove from the oven and layer the tomatoes, breadcrumbs, and pine nuts on top. Return to the oven and roast for 25 to 30 minutes. The fragrance emanating from your oven will be incredible….you'll find the hungry and curious waiting in your kitchen until its done! Every time I make this, the leeks, fennel, and tomatoes release different amounts of juice. Sometimes, only a small amount of water is needed during the first roasting to prevent burning because enough juice releases during cooking. Other times, more water is needed for the second roasting, too, so it's best to monitor during cooking.

To prepare a dish in the style of au gratin includes breadcrumbs and cheese. Classic versions smother vegetables in cream and cheese with a solid layer of toasted breadcrumbs on top. This recipe keeps it lean so individual ingredients add bright sparks of flavor. Each bite tastes a little different, always fun. A small, judicious amount of breadcrumbs soaks up juices without becoming soggy. Adding cheese during cooking can cause it to toughen and brown too much, turning almost leathery in texture. Try grating cheese on top after removing the dish from your oven while it is hot,  just before serving. The aroma and taste are mouthwateringly wonderful!

4 servings. Total roasting time is 45 to 50 minutes.
First Roasting: Leeks and fennel for 20 minutes at 350 F/175 C/Gas Mark 4.
Second Roasting: Tomatoes, breadcrumbs, and pine nuts for 25 to 30 minutes at 400 F/200 C/Gas Mark 6.
Garnish with grated cheese immediately after removing from oven.

8 leeks (medium-size)
1 small fennel bulb, vertically cut into thick slices

Layer in Pan: First Roasting
Sunflower or grapeseed oil for bottom of dish
2 tablespoons (30 ml) water to prevent burning, or as needed
Split leeks
Fennel bulb wedges
Peeled garlic cloves, whole, halved, or thickly sliced
Extra-virgin olive oil to drizzle over
Salt to taste

Second Roasting: An assortment, whole, split, sliced
Firm ripe small-sized Campari, small plum or San Marzano tomatoes
Canestrino di Lucca tomatoes
Brandywine tomatoes
Cherry or grape tomatoes

2 tablespoons (30 ml) water to prevent burning, or as needed
Extra-virgin olive oil to drizzle over
Ground white or black pepper to taste, optional
Ground hot cayenne red pepper, or smoky paprika, or espelette pepper, optional

Sprinkle on Top:
Dry unseasoned breadcrumbs
Whole pine nuts

Garnish: Hand-grate cheese over ingredients immediately after removing from the oven and just before serving
Aged Pecorino, Caciocavallo, Parmigiano-Reggiano, Piave, or Asiago cheese or other hard cheese

Large Ovenproof Dish, Roasting Pan, or Heavy Thick Sheet Pan:
If possible, choose a dish or pan that is at least 13-inches (33-cm) long to hold the leeks

Preparation of Leeks: Leeks are a particularly significant member of the Allium Family, favored for adding rich flavor to dishes as well as served on their own as versatile mild onions. They roast beautifully, possessing a subtle sweetness that marries so well with anise-flavored fennel bulb and end-of-summer's ripe tomatoes.

Unlike many onions that form tight, hard bulbs, the edible part of the leek is a bundle of layered sheaths, sometimes referred to as a stem or stalk. Ranging in color from the creamy white base to dark green tops, the white base to light green part is choice for cooking. Gardeners cover the base with sandy soil so it remains white, tender, and sweet. As sun shines on the top part of the sheaths, they turn light green to dark green. Usually the thick, dark green top is discarded or reserved for other culinary uses, such as simmering in soup, because its thickness requires longer cooking.

Since leeks grow in sandy soil, grains of sand easily get trapped among the layers, so rinse them well before cooking. Trim off the roots and dark green tops. If the outer sheath seems tough, remove it and save for soup. Cut the entire leek in half vertically. Hold one half together with one hand while briefly rinsing under cold water. With your fingers, flip open the layers, like you would with a deck of cards, and watch the sand and grit swirl away in the running water. If the layers separate during rinsing, just push them back together.
Drain, leaving some water clinging to the sheaths to help in roasting, do not pat dry.

Preparation of Fennel: When cooked, fresh raw fennel bulb becomes mild and very fragrant in flavor. Trim off any thin hard bottom from the bulb-like stem known as the base or bulb, and shorten the hollow stalks. Vertically cut the bulb into wedges. Rinse under cold water. Drain, leaving some water clinging to the wedges to help in roasting, do not pat dry.

First Roasting: Preheat the oven to 350 F/175 C/Gas Mark 4. Spread a thin layer of oil in the bottom of the ovenproof dish, then pour in the water to prevent burning. Arrange the leeks, fennel wedges, and garlic inside, spreading them out in one layer if possible. Drizzle olive oil over ingredients. Sprinkle with salt. (Photo above)

Place the dish in the center of the preheated oven. Bake for 20 minutes or until juices are released and leeks and fennel begin to soften. (The aroma of roasting fennel should begin enticing you at the 10 to 15 minutes mark.) If the bottom of the dish appears to be drying out, sprinkle another 2 tablespoons (30 ml) water over the leeks and fennel during the first baking. (Photo below)

Second Roasting: Remove the dish from the oven. Increase the oven temperature to 400 F/200 C/Gas Mark 6. Check the bottom of the dish confirming enough juice/water in the bottom to prevent burning. If the bottom of the dish appears to be drying out and the leeks and fennel have brown edges, sprinkle water over them. Arrange the tomatoes on top of the partially-roasted leeks and fennel. Drizzle olive oil over ingredients. Season to taste with salt and pepper. Sprinkle a small amount of breadcrumbs over, then pine nuts.

Put the dish back into the preheated oven for 25 to 30 minutes or until all ingredients are cooked through and softened, but not mushy. Remove from the oven. Immediately grate your favorite hard cheese over all. Serve directly from the dish or plate. Enjoy.

* FOH Kiln® Blood Orange porcelain serving plate courtesy of Front of the House® company.




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