Whisk together all marinade/dressing ingredients except Parmesan cheese (if using). Pour half of the dressing over the chicken breast in a resealable bag or container. Marinate for at least 1 hour.
If desired, whisk Parmesan cheese into remaining salad dressing (not included in nutrition info).
Assemble salad by tossing kale, radicchio, and cooked lentils with most of the remaining dressing, conserving some for on top of the chicken once cooked. (Keep dressing separate if meal prepping the salad.)
Grill chicken until cooked through, about 5 minutes per side, depending on thickness. Allow chicken to rest for 5 minutes before slicing and placing on top of salads.
Top chicken with remaining dressing and pomegranate arils. Add feta cheese, if desired (not included in nutrition info).