Cut beef lengthwise into 1-inch wide strips; cut crosswise into 1-inch pieces. Sprinkle with 2 teaspoons of the seasoning mix. Heat oil in a heavy stockpot or Dutch oven over medium heat for 5 minutes. Stir-fry beef with onion for 2 to 3 minutes. Season with salt, if desired. Add tomatoes, breaking them up with the back of a spoon, along with corn and remaining 2 1/2 teaspoons seasoning mix. Bring to a boil, reduce heat to medium-low and simmer, uncovered, 18 to 20 minutes.

Spicy Seasoning Mix:
3 tablespoons chili powder
2 teaspoons ground coriander
2 teaspoons ground cumin
1/2 teaspoons garlic powder
3/4 teaspoon dried oregano leaves
½ teaspoon cayenne pepper

Combine all ingredients. Store, covered, in an airtight container.Shake before using. Makes about 1/3 cup.

Makes 4 servings.