Warm the canola oil in a cast iron skillet over medium-high heat.
Toss in the sliced onion, sweet peppers, poblano, and green beans. Sauté for around 7 minutes until they begin to soften and lightly brown.
Push the cooked vegetables to one side of the skillet to clear some space.
Place the zucchini slices directly onto the cleared surface of the hot pan, drizzling with an extra splash of oil if it seems dry.
Sear without moving until the zucchini releases its juices and develops a rich, golden-brown char on the edges.
Turn the zucchini pieces over and continue cooking until both sides are evenly browned.
Combine all the vegetables together in the skillet, sprinkle in the seasoning blend, and toss until everything is thoroughly coated.
Spoon the hot filling generously into warm tortillas, and garnish with fresh cilantro, raw onion, or additional peppers if you like.