Are certain foods better after breast cancer surgery?

Not really. The horse is out of the barn so to speak; but you should avoid foods and supplements with phytoestrogens [plant estrogen compounds] if your tumor is er positive. That includes a lot of soy although small amounts are fine. Also, being overweight or obese is associated with a worse prognosis.
Well balanced. Eating a well balanced diet and maintaining a healthy weight is important. After surgery it helps if you increase the protein in your diet to heal the surgical wounds. If you take supplements, be sure to tell your oncologist and radiation oncologist as these can negatively affect your treatment outcomes.