In a medium bowl, combine tomatoes and next 5 ingredients. Set aside.
For taco butter: In a small bowl, combine butter and taco seasoning. Brush one side of each slice of bread with prepared taco butter.
To Assemble: Place 4 slices of buttered bread on a clean work surface buttered side down. Place 1 slice of pepper-jack cheese over 4 slices of bread. Spoon prepared pico de gallo over each pepper-jack slice. Place remaining cheese slices over pico de gallo. Top with bread slices.
To Cook: Pre-heat a large skillet or griddle over medium-low heat. Place 2 sandwiches in hot pan, butter side down. Grill for 3-4 minutes or until golden brown. Flip sandwich and grill an additional 3-4 minutes or until golden brown. Transfer to a board and cut in half. Serve.