Directions

1. Preheat grill.
2. Using food processor, purée the beans until they are almost smooth, keeping a bit of the bean consistency.
3. Add remaining ingredients and mix together. Form into 6-8 burgers.
4. Grill patties 5-10 minutes per side on an oiled grill or until a digital thermometer inserted into the patty reads 170F (77C). Grill onions next to meat.
5. In a food processor, purée the chilies to a smooth consistency. Set aside 3 Tbsp (45 mL) of the chipotle purée. The chipotle purée can be spicy, so add less than the 3 Tbsp (45 mL) to reduce the heat in the mayonnaise. The remaining purée can be frozen for another use.
6. Clean the bowl of the food processor and add the garlic and brown sugar. Pulse.
7. Scrape down the sides of the work bowl and add the salt, lemon juice, mayonnaise, sour cream and the remaining chipotle purée. Process to combine thoroughly.
8. After onion is cooked, melt old cheddar on top of onions. The cheese helps to hold the meat and onions together nicely on the bun. Garnish with remaining ingredients.