For filling, in a large saucepan, combine the sugar, flour and salt. Stir in sour cream until smooth. Cook and stir over medium-high heat until thickened and bubbly. Reduce heat to low; cook and stir for 2 minutes longer. Remove from the heat. Stir a small amount of hot filling into egg yolks; return all to the pan, stirring constantly. Bring to a gentle boil; cook and stir for 2 minutes. Remove from the heat; gently stir in vanilla. Pour into baked pie shell; set aside.
In large bowl, beat egg whites until soft peaks form. Gradually add brown sugar; beat until stiff peaks form. Spread meringue over warm filling; sprinkle with pecans. Bake at 350° for 12-15 minutes or until golden brown.