Combine flour, cocoa and ancho chile pepper in large bowl. Add beef and toss to coat evenly with flour mixture. Remove beef and reserve any excess flour mixture.
Heat 1 tablespoon butter in stockpot over medium heat until hot. Brown half of beef and remove from stockpot. Repeat with remaining beef, adding remaining 1 tablespoon butter, if needed. Remove beef from stockpot; season with salt and black pepper.
Add bell peppers to the stockpot and cook for about 3 minutes, stirring occasionally. Stir in tomatoes, broth, chipotle pepper, adobo sauce and reserved flour mixture. Return beef to stockpot; bring to a boil. Reduce heat, cover tightly and simmer 1 3/4 to 2 1/4 hours or until beef is fork-tender.
Meanwhile prepare Chipotle Sweet Potatoes:
Place sweet potatoes in large saucepan; cover with water. Bring to a boil; cook 12 to 15 minutes or until tender. Drain, reserving 1/4 cup cooking liquid. Return potatoes and reserved cooking liquid to saucepan; add butter, if desired, chipotle pepper, adobo sauce, salt and ancho chile pepper. Mash potatoes until just blended and slightly chunky.
Serve stew over sweet potatoes.
For less heat, remove seeds from chipotle peppers.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.