Cook pasta in a saucepan of boiling salted water, following packet directions, until tender. Drain, reserving 1/4 cup cooking liquid.
Prepare beans following packet directions.
Heat oil in a large, deep non-stick frying pan over medium-low heat. Add onion, garlic and chilli, if using. Cook for 1 minute. Add tuna, broad beans and lemon juice. Cook for 1 minute or until combined.
Add pasta, reserved cooking liquid and lemon zest to pan. Season with salt and pepper. Cook, tossing, for 1 to 2 minutes or until combined and heated through. Sprinkle with parmesan. Serve.
By Eby