Working in batches, dip mango wedges, halloumi pieces, scallion pieces, and lemon slices in batter, letting excess drip off; add to hot oil. Fry, turning occasionally, until golden and crispy, 1 to 3 minutes depending on size. Transfer to a wire rack set over a baking sheet. Sprinkle fritto misto with remaining 1 teaspoon salt. Serve with chile oil, for dipping.