Cut the tops off the tomatoes and scoop out the seeds. Salt the interior and let them drain, inverted on paper towels while you prepare the chicken salad.
Combine all ingredients except chicken in a food processor and pulse to mix. Add chicken and pulse again to mix and chop the chicken to whatever size you desire.
Scoop the chicken salad into the hollowed out tomatoes and serve on a bed of arugula with a drizzle of olive oil and vinegar.