Step 1Toast the pine nuts in a small skillet over low heat until lightly browned, about 4 to 5 minutes. Set aside.
Step 2Combine the rosemary, lemon zest and garlic in a small bowl and add just enough lemon juice to moisten. Stir together with a spoon, crushing and smearing to make a thick herb paste. The garlic and rosemary should be extremely fine because they will need to cook in a flash.
Step 3Heat the oil in a large nonstick skillet over medium-high heat. When it is very hot, add the squash. Sprinkle with salt and toss to combine, so the squash cubes are evenly coated with hot oil and seasoned with salt.
Step 4Cover tightly and cook without stirring for 2 minutes. Remove the lid and stir the squash. The cooked sides should be starting to caramelize. Cover and cook 2 minutes.
Step 5Remove the lid and toss the squash. Reduce heat to medium, stirring occasionally, until the squash cubes are just tender enough to pierce with a small sharp knife, about 5 minutes. The squash should appear somewhat glazed and browned on much of the surface but should not be so cooked that it falls apart.
Step 6When the squash is cooked, sprinkle with the herb mixture and the remaining lemon juice. Toss to coat the squash, letting the herb mixture sizzle briefly and become aromatic. Taste and adjust the seasoning for salt, lemon juice and black pepper. Scatter the pine nuts over the squash and transfer to a bowl.