To make the filling, soak dried ancho chili in hot vegetable stock or water for 20 minutes until softened.
Place the ancho chilies and soaking liquid into a blender with the garlic, tomato paste, chili powder, salt, and lime juice, and blend for 60 seconds on high speed.
In a sauté pan or non-reactive Dutch oven, heat the olive oil over medium-high heat. After two minutes, when the oil is hot, add the jackfruit pieces and sauté them for 4 minutes until they are lightly golden brown all over.
Add the onions and tomatoes, and continue to sauté for an additional 4 minutes until the onions become fragrant and the tomatoes begin to break down.
Add the contents of the blender to the pan, reduce the heat to low and simmer for about 15 minutes until the jackfruit is tender and most of the liquid has been absorbed.
While you let the filling cool, mix masa harina, salt, sugar, and baking powder in a large bowl.
Mix in the vegetable shortening and add unsalted vegetable stock or water, kneading to form a soft, smooth dough.
Soak corn husks in warm water for 30 minutes to soften. Pat dry, then spread about ¼ cup of dough onto the center of each husk, leaving space at the edges. Place a spoonful of jackfruit filling in the middle of the dough, fold the sides of the husk in, then fold the bottom up, securing with strips of corn husk.
Steam the tamales in a basket with the open end up, ensuring the water doesn't touch them. Cover and steam for 60 to 90 minutes until the dough is firm and doesn’t stick to the husk.
Serve hot with vegan sour cream, cilantro leaves, and minced jalapeño for garnish.