In a large bowl, gently mix all ingredients except the Swiss chard leaves, taking care not to crush the tomatoes. Cover and put in the fridge to chill for 10 minutes.
While the filling chills, boil a pot of water. One at a time, dip the Swiss chard leaves into the boiling water while carefully holding onto the stem. Count to 15 and remove. Leaves should be pliable, but not so soft that they tear. Lay the leaves flat on clean dish towel to soak up extra water, taking care not to tear the leaves or burn your fingers.
One at a time, place the leaves on a cutting board with the flat not spiny side down. Place 2-3 tablespoons of filling in the centre of the largest end of the leaf. Fold the side over the filling and roll the largest end of the leaf forward rolling up the filling and tucking in any odd corners or edges.
Serve with tahini, hummus or another favorite dip or dressing.