The source states there are no references in the food writing about bandeja paisa before 1950 and that it is probably an interpretation of local restaurants of simpler peasant dishes, without naming when it actually took shape as the composed plate now recognized.
What would resolve this A food-history source establishing when bandeja paisa took shape as the combined plate now served in Antioquia and the Paisa region, prior to its first documented reference around 1950.
Openfood historyBandeja Paisa (Wikipedia)