For the beef stew:
1) Combine plain flour, cocoa and ancho chilli pepper in large bowl. Add beef and toss to coat evenly with plain flour mixture. Remove beef and reserve any excess plain flour mixture.
2) Heat 15g of butter in stockpot over medium heat until hot. Brown half of beef and remove from stockpot. Repeat with remaining beef, adding remaining 15g butter, if needed. Remove beef from stockpot; season with salt and black pepper.
3) Add peppers to the stockpot and cook for about 3 minutes, stirring occasionally. Stir in tomatoes, broth, chipotle pepper, adobo sauce and reserved plain flour mixture.
4) 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.
For the chipotle sweet potatoes:
1) 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.
2) Return potatoes and reserved cooking liquid to saucepan; add butter, if desired, chipotle pepper, adobo sauce, salt and ancho chilli pepper.
3) Mash potatoes until just blended and slightly chunky.
4) Serve stew over sweet potatoes.
Cook's tip: for less heat, remove seeds from chipotle peppers.