In large frying pan, heat grapeseed oil over medium heat. Cut zucchini in half lengthwise, then into 1/2 in thick diagonal slices. Add zucchini to frying pan in single layer and cook, stirring occasionally, until nicely golden, about 4 to 5 minutes total. You may need to do this step in 2 batches if your frying pan doesn’t hold all the zucchini in one layer. The goal is to end up with golden brown—not mushy—zucchini. In the last 2 minutes of cooking time, season with a pinch of salt and pepper.