Assimilating can be the hardest part of travel.
The easiest is growing accustomed to new food. Face it, you have to eat. Much easier when the food is cheaper and tastes delicious. Travelling is the perfect outlet if you love food. If you love to eat and on a budget, you need to know the local delights. Lisbon was recently surveyed as the 72nd most expensive city in the world. Compared to other capital cities in Western Europe, food here is cheap. How yummy can cheap food be? Lisbon is home to more than a handful of mouthwatering grub spots. Whether its breakfast, lunch, or dinner, you can find an almost free, or free spot to munch. Lisboetas eat endlessly. Walking these hills will make anyone ravenous.
Two or three small meals during the day and a moderately portioned dinner.
An average daily allowance for a local would be something like this: Breakfast- Coffee or Tea and a pastry of sort, Lunch- Bread with chorizo, Snack- Tremoços (individual yellow beans, eaten like Japanese edamame), Dinner- Bacalhau with potatoes and wine. This plethora of food would bring you to a grand sum of around 5 euros per day. It's mind boggling to see such a low price, compared to spending 10 euros a plate at a restaurant. 
One of my favorite cheap and tasty local spots is Frutalmeidas. A fruit and salad-fusion cafe. Sounds crazy. Well, now with two locations in Lisbon, this once ma and pa joint has expanded to include their grandsons and the food is G double O, D, GOOD. The speciality of Frutalmeidas is the Portuguese delicacy known as 'pasteis de massa tenra.' Known to non-Portuguese as the satisfying; beefpattie, or empanada. In Portugal it is refined and eloquently rendered. Watch out McDonalds this health conscious cafe has its own version of the 1€ menu. Choose from a variety of 6 different cold and fresh juices. Ranging from 1,20 to 1,50 a glass.
One of my favorite cheap and tasty local spots is Frutalmeidas. A fruit and salad-fusion cafe. Sounds crazy. Well, now with two locations in Lisbon, this once ma and pa joint has expanded to include their grandsons and the food is G double O, D, GOOD. The speciality of Frutalmeidas is the Portuguese delicacy known as 'pasteis de massa tenra.' Known to non-Portuguese as the satisfying; beefpattie, or empanada. In Portugal it is refined and eloquently rendered. Watch out McDonalds this health conscious cafe has its own version of the 1€ menu. Choose from a variety of 6 different cold and fresh juices. Ranging from 1,20 to 1,50 a glass.
Soups, pastries (sweet, meat or veggie) and salads average 1.10, 1.20, & 3.00€ respectively. The most expensive thing on their menu is dessert. At Frutalmeidas they make homemade strawberry 'short'cake, 3.20€ for a monster slice. You can find Frutalemeidas #2 behind the Sheraton near the Picoes metro station, or it's 1st and chic locale on Avenida de Roma º45.
Another cheap spot is Cafeteria Italiana, on Rua Dona Filipa de Vilhena, use the Saldanha red line metro exit and cross the garden 'Arco do Cego'. At this tiny cafe, beer is .50cents and a Rissol de Leitão (pig in a blanket) is 1€. If you don't think those eats are cheap enough, how about free food? Yes, free. Food sovereignty is the idea behind Jantar Popular. Issues of sustainable eateries and social awareness at this dinner, make it a concept ahead of its time. A vegan establishment, run by volunteers. 
Jantar Popular (Popular Dinner) offers guests the opportunity to cook, clean, or serve for their dinner or just eat and take part in the banter for 3€. No worries here if you forgot your wallet. Every Thursday of the week, (except in August) bring your culinary skills, your love for veggies, and some political rhetoric to this new Lisbon legend. Check the GAIA.org website for the Jantares Populares weekly location. Almost everyone falls in love with Lisbon. If it is food you like, this is surely the place to have a fork handy. Don't be shy, eat like a local, cheap. The old saying says, the best things in life are free. The cynic's say, nothing is ever free.
In Lisbon, almost everything is always almost free. The good stuff, anyways. By JT