- In a food processor, purée the avocado and lime juice until smooth. Season with salt and pepper. Cover and refrigerate until ready to serve.
- In a large bowl, combine 1 tbsp (15 ml) of the oil with the remaining ingredients and mix thoroughly. Season with salt and pepper. Working with lightly oiled hands, shape the mixture into 8 small patties.
- In a large non-stick skillet over medium-high heat, brown the patties in the remaining oil for 4 minutes, turning halfway through cooking.
- Spread the buns with the avocado mixture and layer with the lettuce and tuna patties. Top with the cucumber.