Preheat your oven to 375°F (190°C) and lightly butter the ramekins or souffle dishes to help the dessert puff and release easily later.
In a small saucepan, combine the orange juice, orange zest, and a tablespoon of sugar. Warm over medium heat until just starting to simmer, then remove from heat and let it cool slightly.
In a mixing bowl, whisk the egg yolks with the remaining sugar and the melted butter until the mixture is smooth and slightly thickened.
Gradually pour the warm orange mixture into the egg yolk mixture, whisking constantly to combine and prevent the eggs from curdling.
Sift the flour and salt into the orange-egg mixture, folding gently with a spatula until well incorporated and smooth.
In a clean, dry bowl, beat the egg whites until soft peaks form. Gradually add the remaining tablespoon of sugar, and continue beating until stiff peaks are achieved and the whites are glossy.
Carefully fold a third of the whipped egg whites into the orange batter to lighten it, then gently fold in the rest, being careful not to deflate the mixture.
Spoon the fluffy mixture into the prepared ramekins, filling each about three-quarters full. Smooth the tops gently with a spatula.
Place the ramekins on a baking sheet and bake in the preheated oven for about 18–20 minutes, or until the soufflés have puffed up and the tops are lightly golden.
Remove from the oven and serve immediately to enjoy their full lightness and delicate citrus aroma. You can garnish with additional orange zest or powdered sugar if desired.