In a mixing bowl, whisk together the flour, salt, and sugar.
In a separate bowl, beat the eggs and add the milk, melted butter. Mix well.
Gradually add the wet ingredients to the dry ingredients, whisking until you achieve a smooth, lump-free mix.
Let the mix rest for about 10 minutes to allow the flour to fully absorb the liquid.
Heat a non-stick skillet or griddle over medium heat and lightly grease with cooking oil or butter.
Pour a small amount of mix onto the skillet, swirling to spread it thinly.
Cook until the edges lift and the bottom is golden brown, then flip and cook the other side.
Repeat until all the mix is used, stacking the Blini as you go.
Serve warm with your favorite toppings, such as sour cream, jam, honey, caviar, smoked salmon, or sautéed mushrooms.