1. Fill and boil your kettle. Snip the sun dried tomatoes into a small heatproof bowl (or leave them whole if you prefer), then pour over enough hot water from the kettle to cover them. Set aside to soak for 15 mins. Pour the rest of the hot water into a large pan, then top it up. Add a pinch of salt, pop on a high heat, cover and bring to the boil.
2. Finely grate the zest from the lemon and set it aside. Squeeze the juice from half the lemon into a blender or small food processor. Peel and grate or crush the garlic and add it to the blender. Pick the parsley leaves off the stems, then add half the leaves to the lemon zest and half to the blender.
3. Tip the pine nuts into the blender. Halve the avocado and scoop out the flesh, discarding the stone, and add to the blender with a pinch of salt. Add 2 tbsp water and blend till smooth, adding a few tbsp more water if you think it needs it. No blender or processor? Crush the avocado with a masher or fork, finely chop the pine nuts and stir them into the avocado with the lemon juice, garlic and oregano. For a chunkier pesto, you can dice the avocado rather than crush it.
4. The water in the pan should be boiling by now. Add the spaghetti and simmer for 8-10 mins till the spaghetti is tender but still with some bite.
5. While the spaghetti simmers, roughly chop the olives and rocket. Drain the sun dried tomatoes, keeping their soaking water.
6. Put a frying pan on a medium heat. Add ½ tbsp olive oil and the breadcrumbs. Fry, stirring, for 2-3 mins till the breadcrumbs are golden brown. Take off the heat and stir in the reserved lemon zest and parsley leaves with a pinch of seasoning.
7. Drain the spaghetti, then tip it back into the pan. Pour in the avocado pesto and add the sun dried tomatoes, olives and rocket. Toss to mix, trickling in a little of the sun dried tomato water to loosen the sauce if you think it needs it.
8. Divide the spaghetti between 2 warm plates and top with the toasted breadcrumbs to serve.