1 medium onion, cut into thin wedges
1 medium red bell pepper, cut into strips
1 medium green bell pepper, cut into strips
3/4 pound thinly sliced deli roast beef, cut into 1/2-inch strips
1/2 cup beef broth
1 (4-ounce) can chopped green chiles
2 teaspoons all-purpose flour
2 teaspoons chili powder
10 tostada shells
1 cup shredded pepper jack cheese
Salsa, if desired
Melt butter in skillet over medium-high heat until sizzling. Add onion and bell peppers; cook, stirring occasionally, 3-4 minutes or until crisply tender.
Add all remaining ingredients except tostada shells and cheese. Continue cooking, stirring occasionally, 3-4 minutes or until mixture is slightly thickened.
Heat tostadas as directed on package. Spoon 1/2 cup beef mixture over each tostada. Top each with 1 heaping tablespoon cheese. Serve with salsa, if desired.
For a spicier dish, choose medium heat level for green chiles instead of mild.