There are lots of restaurants in Cairns, but today we recommend Grill'd, a gourmet burger with a solidary background. The burgers are great (10-15 AU$), not to mention their hot chips (AU$ 5). In addition, each month they make donations to 3 NGOs, and are customers who choose how much to each, you'll see how! It is located at 77 Esplanade (between Shield's and Aplin).
But if what you want is oriental food, so we love the Ganbaranba (12-20 Spence Street), a very basic place but with first class gyozas and noodles! Estimate about AU$ 25 per person.