Unfortunately, there isn't a common, commercially available "aseptic tomato paste" made from unripe tomatoes. The reason for this is that green tomatoes have a significantly different flavor profile than ripe ones, and they often don't reduce down to a thick paste in the same way.

DIY Options:

If you're keen on experimenting, here are a couple of options:

1. Green Tomato Sauce: You can make a green tomato sauce that can be thickened and used as a substitute for paste. This would involve roasting or boiling green tomatoes, blending them with herbs and spices, and then reducing the sauce to a thicker consistency.


2. Combination: You could combine green tomato sauce with a small amount of traditional tomato paste to achieve a desired flavor and consistency.

Note: The flavor and texture of a homemade green tomato paste or sauce will vary significantly depending on the specific variety of green tomatoes used, the cooking method, and the addition of other ingredients.

Would you like me to provide a recipe for a green tomato sauce that could be used as a base for a paste-like substance?