To a large skillet, add the oil, onion, bell pepper, and jalapeno. Saute over medium heat for 4-5 minutes.
Add the fajita seasoning, chili powder, cumin, and salt. Cook for another minute.
Now, add the zucchini and cook for another 5 minutes, until it softens a bit.
Lastly, add the corn and black beans and cook for a few minutes, until everything is heated through. Taste to see if the veggies need more seasoning, then add the lime juice and stir, mashing the black beans a bir. Set aside.
Preheat the oven to 400°F. Line a large baking tray with a silicone baking mat or parchment paper.
Lay out the tortilla on a flat surface and add about 3 tablespoons of filling to it. Roll up the tortilla tightly and place it seam side down on a baking tray. Repeat this step until all of the filling is gone. (You'll have about 10 taquitos).
Using a pastry brush, brush a thin layer of oil on each taquito. Bake 25 minutes, until the tortillas start to brown.