Place cubed sweet potatoes in a pot of salted water. Bring to a boil and cook for 10–12 minutes, or until fork-tender. Drain and mash until smooth. Let cool slightly.
In a large bowl, combine mashed sweet potato, tuna, bell pepper, onion, garlic, egg, chives, lemon juice and paprika. Mix well until evenly combined.
Scoop the mixture and shape into small cakes, about ½ inch thick.
Heat a skillet over medium heat with a drizzle of olive oil. Cook the cakes in batches for 3–4 minutes per side, or until golden brown and heated through. Avoid overcrowding the pan.