In a shallow bowl, combine flour and half of seasoning mix. Add pork, a few pieces at a time, and toss to coat; shake off excess.
In a large skillet, heat canola oil over medium-high heat. Add pork; stir-fry until browned, 3-4 minutes. Remove with a slotted spoon; cover and keep warm.
In same skillet, heat olive oil. Stir-fry onion and peppers until crisp-tender. Chop tomatoes; add to skillet. In a small bowl, combine remaining taco seasoning and reserved tomato juices. Add to skillet. Bring to a boil; cook and stir until thickened. Reduce heat to medium-low. Return pork to skillet; heat through.