Clean, pat dry, and thinly slice the mushrooms.
Heat a frying pan on medium-high heat. Once it's hot, pour in the olive oil and swirl it around.
Now add your sliced mushrooms and give it a quick toss. Do not season or stir your mushrooms at this stage for 2 to 3 minutes.
Once you see that the mushrooms are caramelizing at the bottom, season them with salt and pepper. Toss or flip them in the pan and let them get caramelize on the other side for another 2 to 3 minutes.
Add your drained and rinsed black beans along with sweet corn and chopped onions to the pan. Season everything with cumin, coriander, chili powder & smoked paprika. Adjust the salt if necessary and bring down the heat to medium-low.
Once the onions are soft and translucent, turn the heat off and transfer the mixture to a serving bowl. Sprinkle in your chopped cilantro, squeeze in the lime juice and stir to combine.
In a skillet over medium-high heat, start toasting your tortillas one at a time until crisp and slightly charred around the edges.
Assemble your tacos and top it with your favorite condiments.