In a small saucepan, combine the sugar, water, and lemon juice.
Bring to a boil over medium heat, stirring occasionally until the sugar has dissolved.
Reduce the heat and let it simmer for about 5 minutes, or until the syrup thickens slightly.
Remove from heat and stir in the rose water or orange blossom water if using. Set aside to cool.
In a large bowl, mix together the flour, cornstarch, sugar, and salt.
In a small bowl, dissolve the yeast in the warm water and let it sit for 5 minutes until foamy.
Add the yeast mixture, yogurt, and egg to the dry ingredients. Mix until a smooth batter forms. The batter should be thick but pourable.
Cover the bowl with a clean cloth and let it rise in a warm place for about 1 hour, or until it has doubled in size.
Heat oil in a deep frying pan or pot over medium heat to 350째F (175째C).
Using a small spoon or ice cream scoop, carefully drop spoonfuls of the batter into the hot oil. Fry in batches to avoid overcrowding.
Fry the Luqaimat until they are golden brown and puffed up, about 2-3 minutes per side. Use a slotted spoon to remove them from the oil and drain on paper towels.
While the Luqaimat are still warm, dip them into the prepared syrup, ensuring they are well-coated.
Transfer the syrup-coated Luqaimat to a serving plate.
Enjoy your meal!