Add the cherries, sugar, pinch of salt, and 1 cup water to a small saucepan.
Simmer over medium heat for 5–6 minutes, stirring occasionally, until the sugar fully dissolves and the cherries become very soft.
Remove the saucepan from the heat and let the mixture cool for about 10 minutes.
Transfer the cherry mixture to a blender and blend until completely smooth.
Pour the blended mixture through a fine mesh strainer into a large pitcher, pressing gently to extract all the liquid while leaving the skins behind.
Add the fresh lemon juice and remaining 3 cups cold water to the pitcher and stir thoroughly until fully combined.
Refrigerate the lemonade until completely chilled.
Taste the lemonade once cold and adjust if needed by adding extra sugar for sweetness, more lemon juice for tartness, or a splash of water if serving without much ice.
Fill glasses with ice and pour the cherry lemonade over the top.
Garnish with lemon slices and fresh cherries before serving.