Pit the olives and finely dice them. Add to a small bowl along with the chopped almonds, grated garlic, grated lemon zest, lemon juice, and olive oil. Season with salt and pepper and stir to combine. Set aside until needed.
Cook the pasta according to the package instructions. Cook until the pasta is cooked al dente, then drain and preserve about 80ml or 1/3 cup cooking water.
While the pasta is cooking, make the sauce. Place a skillet over medium heat. Add olive oil, diced onion, garlic, parsley, grated lemon zest, and capers. Rinse the capers under running water before using them. Reduce the heat to low, and saute for about 5 minutes. Add the tomato passata and cook for another 5 minutes. Drain the canned tuna, add to the sauce, gently stir and cook for a minute.
Canned Tuna Pasta with Tomatoes, and Capers
Add the drained spaghetti to the sauce and toss to combine. If necessary, add some reserved pasta water to get a silky pasta sauce. Divide between four plates and serve with the homemade olive dressing.