In a pan over medium heat, add the onion and saute until translucent. Add in the garlic, tomato paste, vegetable broth and spices. Saute until fragrant, an additional 2 minutes.
Add in the drained and rinsed cans of black beans and vegetable broth, and stir until combined with the spices and tomato paste.
Using a potato masher or the back of a fork, mash the beans into a thick paste. Finish with a squeeze of lime.
Coat a sheet pan with spray oil, and lay out the tortillas. Transfer the mixture 2 tablespoons at a time onto the tortillas, and top with vegan cheese if using. Fold in half, making sure to seal the tortillas so they don't flip open in the oven.
Place in the oven for 5 minutes, then flip and bake the other side until crispy. While the tacos bake, make the herb dressing by adding all ingredients to a blender and blitzing until combined.