The recommended approach for handling tabular data when building a REFramework transactional project in UiPath is to utilize a DataTable variable to store and process the tabular data. A DataTable variable can hold data in a tabular format, with rows and columns, and can be easily manipulated using built-in activities such as Read Range, Write Range, Filter Data Table, For Each Row, etc. A DataTable variable can also be used as the input for the Get Transaction Data state in the REFramework, which retrieves each row of data as a transaction item for processing. References: [UiPath Studio Guide - Data Tables], [UiPath Studio Guide - The REFramework]