Beverage options include a cooler of exotic fruit juices and imported sodas and a large jug of water. There's warm rice in a large rice steamer, a staple that is replenished many times throughout the day.
Although most diners are Indonesian, drawn to the smells and tastes of the vibrant country they've left behind, a growing number of locals have discovered, and become addicted to, Widjojo's zesty cooking.
Customers like Aaron MacLennan, a teacher at Hunter Elementary in Kensington, who first tasted Indonesian cooking in Jakarta, where he recently spent two weeks.
"This is comparable to what I ate there," he said. "It's the best Indonesian food in Philadelphia, a great mix of Indian and Chinese flavors. I heard that Indonesian women have to know how to cook 100 dishes when they get married so their husbands don't go out to food stands to eat. I believe it!"
Widjojo opened her modest eatery seven years ago, the first true sit-down cafe in a neighborhood that is home to many of the city's estimated 5,000 Indonesians. She had run a restaurant for many years in the Indonesian consulate in New York where she fed dignitaries including former Nixon security adviser Henry Kissinger and Indonesian President Suharto.
When the consulate cafe closed in 1989, she concentrated on catering, until friends from Philadelphia persuaded her to bring her culinary prowess south. She now divides her time between New York - her husband, Hari, is a longtime waiter at the Ritz-Carlton - and her business in South Philly, where she lives next door to the restaurant.
Her daughter Malia, who plans to attend J&A Culinary School on Broad Street, helps out in the kitchen.
The Indonesian population in Philadelphia has been slowly rising since 1998, the year of a large-scale emigration of Indo-Chinese from the main island. As is the case with any cultural migration, the newcomers to Philadelphia brought their cuisine along for the ride.
If you've never tasted Indonesian cuisine but are open to bold Asian flavors and ingredients, you're in for a treat. Indonesia's table is laid with a multitude of influences and migrations, from the earliest Malay people of Southeast Asia, who introduced rice and stir-frying in what would later be called a wok, to Indian merchants and missionaries who preached the gospel of curries and turmeric along with Hinduism and Buddhism.
Arab traders brought grilled meats and kabobs; Portuguese and Dutch introduced tomatoes and carrots, and in turn brought heady spices like cardamom, lemongrass and coriander back to Europe.
Indonesia, composed of about 13,000 islands arranged like a necklace between the Indian and Pacific oceans in Southeast Asia, offers cuisine as varied as its landscape, which ranges from lush rain forests to emerald-green rice fields and active volcanos.
Although Aldo Siahaan has lived in Philadelphia for eight years and adores all kinds of food, from sushi to Italian, when he needs a dose of home, he wanders to his adopted South Philly neighborhood.
"We all love spicy food, the more spicy, the more we like it," said Siahaan, a founder of the Philadelphia Praise Center, a Christian church at 17th and McKean streets.
As part of his ministry, Siahaan, a native of Jakarta, works with immigrants trying to cope with a new language and culture in America. "When everything seems strange, we can always go to an Indonesian waroeng [simple cafe] or shop. It's a gathering spot that feels familiar," he said.
One of Siahaan's favorite dishes is soto betawi, a savory meat soup fragrant with kaffir lime and coconut. "It reminds me of back home," he said.
The Indonesia Store, at 1701 S. Bancroft St., was the first Indonesian shop to open locally in 2001. Amir Atmodjo helps his parents in the family business, a convenience store that is a central meeting point for many Indonesians in the area. They can cash a check, get help with paperwork, pay bills and wire money while they're picking up freshly made Indonesian takeout for dinner.
Like many of these small shops, it's open seven days a week, offering dishes like nasi cah kangkung, a small, whole fried fish with sambal, a chili sauce, for around $5.
Indonesian food is vegetarian-friendly, with tofu and its fermented by-product, tempeh, an ingredient in many curries and stir-fries.
Not everything is super-spicy. Gado gado is a warm salad of boiled cabbage, carrots, bean sprouts and Chinese lettuce topped with boiled egg and a sweet ground-peanut sauce. Sweet-and-sour fried sole is battered and drizzled with a sauce of lemongrass and pineapple. A must-try dish is made with collard greens; it's a rich vegetable stew flavored with garlic, onion, red pepper and coconut milk.
Frying food is embraced as a national pastime, with fried rice (nasi goreng) and fried noodles (bakmi goreng) often served garnished with bits of vegetables, meat and fried egg.
At Hardena, Widjojo serves fried chicken that takes hours to make, a favorite with the locals. But her satay might be the best seller; on an average day, she grills as many as 300 skewers of the tender, marinated beef, chicken or goat.
Laura Cohn, an artist and Belmont Hills resident who spent years in Indonesia and speaks the language, visits Hardena and the other little shops in the neighborhood for a reminder of the cultural warmth and camaraderie she feels in her annual sojourns to Indonesia. She also stocks up on ingredients like the sweet soy sauce found in many dishes, and picks up takeout treats for her husband, Bill, and their son, Daniel.
"This is the real thing," she said. "When I feel homesick, I come here."