Add the pineapple juice, brown sugar, ketchup, soy sauce, ground ginger, and garlic to a small bowl and mix well. Reserve 2 Tablespoons of the marinade mixture to add to the tomato relish.
Pour the remaining marinade mixture into a gallon size plastic bag and add the chicken. Seal the bag and place in the refrigerator for at least 30 minutes or up to 24 hours. (The longer the better!)
Loosely thread the chunks of marinated chicken on the skewers. The pieces should be touching, but not packed together or compressed.
Thread the cherry tomatoes on the skewers.
Set up your grill for direct heat cooking. Clean and oil the grate and place on the grill.
When the grill and grates are hot, place the chicken skewers, cherry tomato skewers, scallions and lemon halves cut side down on the grate and cover.
Grill the chicken for about 15 minutes or until done, turning every few minutes or so.
Grill the vegetables for about 10 minutes or until charred, turning scallions and tomatoes as needed to brown evenly.
Remove the chicken and vegetables from the grill, tent the chicken with foil and let it rest for about 10 minutes.
In the meantime, mix the reserved marinade, butter, and honey in a small saucepan over medium heat until the butter is melted.
Chop the scallions, squeeze the juice out of the lemons, and combine with the tomatoes and honey mixture in a small bowl. Using a potato masher, coarsely mash the tomatoes. Add salt and pepper to taste if needed.
Serve the tomato relish over the grilled chicken and garnish with chopped basil if desired. Enjoy!