Slice zucchini lengthways. Place in a bowl and sprinkle generously with flaky sea salt to draw out water and season the zucchini. Leave for 15 - 30 min. Rinse and pat dry. Trim root end of the scallions. Transfer to a baking sheet along with the scallions, and two cloves of garlic, skin on. Make a glaze by mixing together the maple syrup and olive oil, plus a pinch of flaky sea salt. brush the zucchini and scallions with half the glaze. Grill in an oven on medium-high, turning as needed and brushing on more glaze. Remove the quicker-cooking scallions first when they are soft and browned. The zucchini will take approx 10 min. to cook and brown a little, depending on the strength of your grill.