Preheat oven to 375 degrees Fahrenheit and line 1-2 baking sheets with parchment paper.
Place sliced sweet potato in a medium bowl. Mix with 1 teaspoon olive oil, making sure the sweet potato gets evenly coated. Spread out evenly on baking sheets, making sure not to touch and bake for 20 mins, flip, and bake for 10 more minutes until cooked through and golden brown.
While the sweet potato bakes, makes the bruschetta. Mix together the tuna (make sure NOT to drain it), cherry tomatoes, garlic, basil, olive oil, lemon juice, and salt and pepper.
Once sweet potatoes are done, let cool for a few minutes and then evenly distribute bruschetta mixture among toast. Top with lemon zest if using.