I go to Salzburg every year and without fail always visit the Mundenhamer Brau restaurant.
The food is a mix of traditional German/Austrian with the odd British style meal thrown in. The restaurant is hugely popular with locals and tourists alike. Prices are very reasonable indeed ranging from 8-20 Euros, and portions are huge.
The restaurant is large and has a fair few tables, but is always packed. When full, you never feel cramped, and service is always impeccble. If you go early evening, you should be able to get in without reservation. Reservations are a must for Saturday day times and late evenings.
The staff are very friendly and speak good English if your Austrian is a bit rusty. I have been around 6 times in the last 3 years, and each time the same owners are serving and waiting tables. They are always very welcoming and friendly.
In addition to the great food, the restaurant also has a big selection of traditional beers.
My personal favourite is the steak and noodles in onion gravy. It's very tasty, and filling, but leaves you with enough rooms to try their warm pancakes served with ice cream and chocolate sauce.
The restaurant is opposite the mirabell palace where the tour guide trip sellers base themselves.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.