Mix the sugar, salt, milk and Karo syrup in a heavy 3-quart pan.
Cook to a soft ball stage and then remove from heat.
Stir in butter and vanilla and beat until cool.
Add pecans and drop by tablespoon onto wax paper.
When firm, store in a closed container.
Makes about 2 dozen three-inch pralines.
The Sugar Substitution Factor
Swapping brown sugar for light muscovado alters the moisture content and introduces deeper molasses notes, yielding a chewier candy. Confectioners sugar cannot replace granulated sucrose here because added cornstarch prevents proper crystallization during the cooling phase. Heavy-bottomed pans distribute heat evenly, preventing scorching while the dairy and sugars combine.
Reaching the Soft Ball Stage
Precision dictates success when boiling the mixture to the 235 degree Fahrenheit soft ball stage. Cooking past this threshold produces brittle, hard candy, while removing the pan too early leaves a runny syrup that refuses to set. Vigorous beating after adding the butter and vanilla forces sugar molecules to reform into micro-crystals, creating the characteristic opaque, grainy texture.
Storage and Freezing Guidelines
Drop spoonfuls onto parchment paper quickly before the candy hardens in the pot. Store finished pralines in an airtight container at room temperature for up to five days. Extended storage requires freezing for up to two months, though thawing must occur inside a sealed container to prevent ambient humidity from dissolving the crystalline surface.