Mix tomatoes (undrained!) through soy sauce in a small sauce pan over medium heat.
Mix 1 tbsp cornstarch with 2 tbsp water and whisk into sauce. Bring to an almost-boil and reduce heat to thicken. If necessary, add an additional 1 tbsp cornstarch with 2 tbsp water to reach desired thickness (for these sandwiches, I went the extra thick route so I wouldn't make a mess eating them!)
Lightly toast hoagie buns in the oven, if desired. Add 3 – 4 meatballs per sub (or whatever will fit) and top with cheese sauce.
Recipe by Hidden Fruits and Veggies at https://www.hiddenfruitsandveggies.com/2013/04/22/chili-meat-ball-subs-vegan/