Place grated zucchini in a large colander set over a medium bowl or in the sink. Press with paper towels or a kitchen towel to remove as much liquid as possible.
In a large nonstick skillet over medium-high heat, warm a layer of olive oil, then add onion and cook, stirring frequently for 3 to 4 minutes, until the onion begins to soften. Add the zucchini and corn and stir to combine.
Cook, turning the mixture every couple of minutes, until the zucchini is just turning golden at edges, 5 to 8 minutes. Add butter if using and squeeze lemon over top. Turn off heat and stir in dill. Add seasonings to taste.
Serve warm or room temperature.
