In large (3-quart) heavy saucepan, combine granulate sugar, soda, buttermilk and salt. Cook over high heat about 5 minutes (or to 210F on candy thermometer); stir often and scrape bottom of pan. Mixture will foam up. Add butter and margarine and pecans. Over medium heat, continue cooking, stirring constantly and scraping bottom and sides of pan until candy reaches soft ball stage (234F on candy thermometer). Remove from heat and cool slightly, about 2 minutes. Beat with spoon until thick and creamy. Drop from tablespoon onto sheet of aluminum foil or waxed paper. Let cool.
Makes about 20 pralines, 2 inch in diameter.
Cajun Country -- New Iberia, Louisiana