Eataly has finally opened its long-awaited, three-story food hall at Westfield Valley Fair. Spanning 45,000 square feet and housing a rooftop restaurant, Eataly Silicon Valley provides Italian food lovers with a chance to do their grocery shopping, browse specialty foods and enjoy wine, pizza and gelato all in one place.

A store with over 10,000 products can be overwhelming, so we enlisted the help of Viola Buitoni, an Italian food expert who teaches cooking lessons both in San Francisco and in Italy. She'll be releasing a cookbook named "Italy by Ingredient" next year and serves as the expert food adviser for San Francisco's Italian Consulate. We toured Eataly as part of a media tour before the store's opening.

From dried pastas to fresh fish, here's Buitoni's guide to Eataly's must-have products:

Pope's salt: According to Buitoni, naming a food after a religious office means that the item is "very flavorful and a little (bit of a) secret." In Italy, religious leaders historically received the best products, usually for free.

Pope's salt has less of the bitter, mineral flavor that defines many other salts since it comes from the Adriatic Sea. Buitoni uses it to season already briny fish and earthy root vegetables.

Pizza: Eataly's Neapolitan pizza is crafted in partnership with Naples-based chain Rossopomodoro, and the buffalo mozzarella is imported from Italy since the store hasn't been able to recreate it locally (fresh mozzarella is made in store from cows' milk.)

Buitoni appreciates the mozzarella that tops Eataly's pizzas and says that the cheese should be judged by its milkiness. It shouldn't squeak when bitten into either.

Umbrian lentils: Perhaps Buitoni's favorite item in the entire store, these lentils hail from her home region of Umbria. She says that they stay whole, cook within 20 minutes and don't need to be presoaked.

Buitoni recommends sauteing the intensely flavored lentils with some pancetta, a bay leaf, tomato paste and flavorings including celery, carrot, onions or garlic. She then deglazes the pan with red wine and slowly braises the lentils in a bit of water.

Dried pasta: Buitoni stares closely at each pasta box looking for striations and imperfections. She points to the rough edges and streaks of white and yellow in the pasta made by Campofilone as an example of what she's looking for. These details show the use of real eggs and that the pasta hasn't been overworked. Provenance is also significant, and many of Eataly's selections come from Gragnano, a territory known for its dried pastas.

A surprising note from Buitoni: pasta makers love American Manitoba wheat, which has a high protein content that creates strong gluten development. She says that generally, pastas made with only Italian grains have a more intense flavor, but that the lack of high-protein flour might affect the texture. Lastly, she recommends looking for pasta that's boxed instead of bagged, especially when buying fragile shapes.

Mandarinata: While Buitoni finds most American sodas too cloyingly sweet, this sparkling citrus beverage is her pick for a cooling summertime beverage.

All sorts of tomatoes: Buitoni points out that even among the acclaimed San Marzano tomatoes, some producers create better products than others. She highlights the cooperative-backed Gustarosso brand for its longtime relationships with farmers.

She also loves triple-concentrated tomato paste, which gives an "unparalleled" depth of flavor and is hard to find here in the United States. She especially recommends it for vegetarians looking to lend their dishes richness.

At the end of the tomato aisle, Buitoni points to datterino tomatoes packed in water. She says that companies packing tomatoes in puree might use subpar tomatoes for the surrounding puree. These small tomatoes cook quickly on high heat with oil and garlic or can be smashed raw and smeared onto bread.

Scorpionfish/rockfish and monkfish: These two fishes can be found in the Mediterranean, and Buitoni finds them delectable in acqua pazza, poached in tomatoes and water with black olives, garlic and basil. She also roasts them with potatoes and zucchini.

Orecchiette di grano arso: Made from "burnt wheat," this pasta comes from Puglia and signifies the resourcefulness of commoners and sharecroppers. Burning the fields was a part of the region's agricultural cycle, and residents scavenged up the leftover wheat. As economic conditions improved, grano arso became associated with poverty and started to fade away as a culinary tradition. About 10 to 15 years ago, locals started reclaiming the tradition of grano arso, and returned to producing this pasta with an ashy flavor that complements the wild herbs and bitter greens common in Puglia.

Balsamic vinegar: Buitoni says to look for both the word "traditional" and the proprietary round bottles that mark the highest qualities of balsamic vinegar. Extravecchio vinegar from Modena is aged for at least 25 years and retails for $199 a bottle at Eataly. Buitoni compares these vinegars and their slightly younger relatives to black honey and says they're the only ones that merit paying a truly premium price. Cheaper alternatives are fine for cooking and making heated sauces.

Hazelnuts from Piemonte: Buitoni enjoys these hazelnuts as snacks, in baking, over yogurt and in salads and sauces. They are said to have a richer flavor than most commercially produced hazelnuts.

Gelato: The gelato section at Eataly Silicon Valley differs from the counters at the megastore's other locations thanks to a partnership with third-generation gelato chef Patrizia Pasqualetti. A resident of San Francisco and former head gelato maker at the city's GIO Gelati, Pasqualetti is striking out on her own and continuing her family's tradition of creating seasonal sweets by opening shops in Yountville and Malibu.

Marvis toothpaste: The end of a great day of eating has to end with proper hygiene, and Marvis toothpaste is a must in Buitoni's suitcase whenever she returns from Italy. The brand's traditional flavors include ginger, cinnamon and Amarelli licorice.

Eataly Silicon Valley, Westfield Valley Fair, 2855 Stevens Creek Blvd., Santa Clara; 650-456-9200, eataly.com. Instagram: @eatalysiliconvalley.