Budget
Okonomi-mura
Three floors packed with no less than 27 okonomiyaki shops. This, indeed, is Hiroshima culinary nirvana. They all serve beer and okonomiyaki with some variations kim-chee oysters, etc, and they'll all start clamoring for your business as soon as you walk through the door. It's right behind PARCO, with a distinctive 'Okonomi-mura' arch out front.
Otis!
Serving Tex-Mex in Hiroshima for more than twenty years, Otis! is the most vegetarian/vegan/organic-friendly restaurant in town, with items clearly marked on their English menu. In addition to tacos, burritos, enchiladas, and nachos, they have a varied of made-from-scratch bakery items including muffins, brownies, and rye bread, as well as a handful of other items not easy to find in Japan such as jambalaya and lentil curry with brown rice. The atmosphere is more that of a small live house or indie cafe than a restaurant, with the walls covered in graffiti messages from passing musicians, and the corners stacked with audio equipment and unusual stringed instruments-- they also have a fairly busy schedule of live music, both Japanese and international.
Sankanou
A tiny okonomi shop in a little back alley near the railroad tracks and beside Hiroshima Station. The shopkeep speaks English and is a friendly, enthusiastic young manga fan. He's decorated his shop with Gundam models, moe-moe figurines, manga posters and baseball and wrestling action figures. This shop serves okonomiyaki in the traditional method, directly on the hot griddle built into the table in front of you. Highly recommended for a visiting anime/manga nerd in search of true Hiroshima okonomiyaki the same way Ukyo serves it in Ranma ½!
Jupiter Import Foods
If you're making dinner at your hotel or missing a certain snack, Jupiter packs a lot of imported foods and alcohol into a pretty small space, with a good selection of standard Western fare and others, particularly Thai and curries. They tend to have a basket or two of free dessert samples near the entrance. There's an entrance right outside the Shinkansen ticket machines and outside the station as well.
Okonomi Monogatari Ekimae-Hiroba
Another okonomiyaki village, with almost twenty shops sharing the same floor, in a vaguely Edo-ish atmosphere. This one is across the street from JR Hiroshima station, next to the Fukuya department store and across from the central post office. You'll see a banner sign outside.
Organ-za
If you and your companion have completely different tastes in mind, Organ-za offers dishes from India, Japan, Thailand, Vietnam, and others direct from the imagination of a capable and creative chef. English menus are available. There's also a full bar tended sometimes by Chie from the late, lamented Alcoholiday and frequent live music.
Tachikoma
A tiny okonomoyaki shop where locals go, with very friendly owners. The okonomiyaki is quite good and filling, and there's beer to enjoy with it.
Midrange
Cusco Cafe
Spanish and Peruvian cuisine including paella and ceviche, plus a smattering of other dishes such as pizza and pasta. There's a pleasant, eclectic ambiance to the decor and the menu, and a full bar if you're not in a hurry.
J Cafe
A stylish cafe with a menu of lighter fare such as waffles, sandwiches, and crepes. The comfy red couches make it a place to hang out for a while, which locals do — note the late hours. It's just off the intersection of Heiwa-o-dori and Jizo-dori. The circle 'J' logo is easily mistaken for an @ sign.
Maison de Croissant
Lovely little macrobiotic cafe with a health food store downstairs. Limited menu, lots of drinks. Try the pita sandwich set ¥1000. Lunch is only served until 2:30PM; after that, it's desserts and drinks only. From the Peace Park on Heiwa-Odori, go west away from downtown and JR Hiroshima Station — after the second bridge, turn left at the third traffic light, and it's on the right side of road between a post office and a gas station.
Spicy Bar Lal's
Indian and Nepali cuisine, with several good course dinners for individuals and pairs. Befitting the name, they're specific about their spiciness: you can choose a strength from 1-100! Basic English menus are available. It's just off Hon-dori, near the post office.
Nanak
Probably the biggest of Hiroshima's many good Indian restaurants. Individual sets are available, but ordering as a group is the best value. It's easily recognized by the uniformed fellow in the window booth facing the street, hard at work on the day's curry and oblivious to the passersby. English menus are available.
Kurobutaya
Offers an English menu and a variety of small dishes. Perfect to have a taste of many things. Nice izakaya-like ambiance with jazzy tunes and friendly staff.
No-no Budou
A non-smoking, healthy "viking" buffet style restaurant with a wide selection of curries, tempura, and other Japanese dishes, some of which are made with locally-grown and organic ingredients. They have a great selection of juices, tea, and coffee, too.
Roopali
Good food on the quieter Shinkansen side of JR Hiroshima station. A wide range of curries are on offer, and there is plenty to eat for vegetarians. The thali sets are good and filling. Comprehensive English menus are available, and it's kid-friendly to boot. If you're just arriving in Hiroshima on an empty stomach, you can't do much better than this.
Shichida Life Cafe
Offers numerous organic and vegetarian options, such as salads, sandwiches, veggie burger, rice and noodle dishes; also a good selection of teas, coffee, and other beverages.
Top end
Creative Sushi Nobu
This small, stylish restaurant near the Peace Park serves up terrific sushi rolls of Chef Nobu's inspiration. He used to live in the U.S., and speaks fluent English. But if it's local flavor you're after, taste what he can do with the conger eels native to Hiroshima. Note: This place may be closed now I could not find it and was told it had been replaced by a Korean restaurant.
Kanawa (Oyster Boat)
Docked just south of the Peace Park, this floating restaurant offers some of the tastiest oysters in Hiroshima, along with lovely traditional decor and nice river views more so at night. There's plenty of room aboard, but it does fill up, so reservations are suggested.
Sumojaya Takabayama
Chanko nabe, the food of sumo wrestlers, is a filling, fun, and healthy dish for anyone to enjoy, especially on colder days.