Heat the 1/4 cup olive oil in a large Dutch oven over medium heat. Add the chopped zucchini and onions. Season with salt and pepper and toss to coat. Increase the heat to high and add the water. Bring to a boil and cook for 8 minutes.
Meanwhile, in a large skillet, heat the remaining 2 tablespoons olive oil over medium-high heat. Working in batches, lay the sliced zucchini in a single layer in the skillet. Cook until golden, about 1 minute per side. Transfer to a plate lined with paper towels. Sprinkle with salt. Continue until all the sliced zucchini is cooked.
Working in batches, transfer the soup to a blender and blend until smooth. Add salt and pepper to taste, pour into bowls, drizzle with Lemon Oil and top with the fried zucchini.
Combine the oil and lemon in a blender and blend until smooth. Strain through a fine-mesh sieve set over a liquid measuring cup. Set the lemon oil aside until ready to use. The oil can be stored in an airtight container and refrigerated for up to 3 days.
When blending hot liquid, first let it cool for five minutes or so, then transfer it to a blender, filling only halfway. Put the lid on, leaving one corner open. Cover the lid with a kitchen towel to catch splatters, and pulse until smooth.