Our grapes are in as is the tulsi, so we gave this a try
Ingredients for syrup:
1.5 cups of grapes
1/3 cup of sugar
20 tulsi leaves
2 TBS lemon juice
2 pinches of black lava salt
Directions for immediate syrup
Place the ingredients in a blender and pulse to not grind the seeds with a cup of water
Filter through cheesecloth and then filter a second time through a coffee filter. Serve 1/4 of a cup of syrup over ice with seltzer water.
Directions for water bath canning
Place all the ingredients into a sterile quart jar, grapes whole, filling the jar with boiling water. Can for 10 minutes. Check that the jars sealed. Filter through cheesecloth smashing the grapes. It does not need the second filtering.
This version is more dilute, and the tulsi flavor is less pronounced, but it is shelf stable to serve later in the year.

