Sandoval (elbow) threw a bullpen session Tuesday, Jen McCaffrey of The Athletic reports.
The bullpen session -- which featured 16 fastballs -- was Sandoval's first since he underwent internal brace surgery on his left elbow last June. Sandoval is slate to throw off the mound twice per week as he continues to ramp things up. The hope is that the left-hander can contribute to the Red Sox at some point during the second half, but there's no concrete timetable for him at this point.