Mix together the sour cream, light corn syrup, molasses, salt, rum (optional) and two cups of the granulated sugar.
Melt the remaining cup of granulated sugar in a heavy bottomed pot, stirring constantly until it is caramelized.
Pour the mixed ingredients into the melted sugar at first slowly, stirring rapidly, so that it mixes with the sugar.
Then pour the rest of the mix in.
Much steam will be released in this process, so it is advised to wear a cooking mitten on the hand that is used to stir.
Cook without stirring until the mixture reaches a temperature of 250 F (midway between the softball and hardball stage.) To accurately measure the temperature, calibrate and adjust your thermometer for you elevation.
Place the thermometer in a pot of water and bring it to the boiling point. Note the reading on your thermometer.
Apply the difference between the boiling point shown and the true boiling point of 112 F to the 250 F true praline temperature. If, for example, the thermometer shows the water boiling at 202 F, then subtract 10 degrees from the praline temperature of 250 F to get the reading of 240 F at which the praline syrup is done. Add the cleaned pecans all at once. Fold and mix the pecans into the syrup until thoroughly mixed.
Drop by spoonfuls onto oiled parchment paper or onto an oiled marble surface. If you wish to individually wrap your fresh pralines, use wax paper.
Do not use plastic wrap, as it will stick to the candy.
Notes:: * Do not use "lite" or "non-fat" sour cream