Microwave olive oil with Knorr® Chicken flavor Bouillon in small microwave-safe bowl at HIGH 30 seconds; stir and cool slightly. Process bouillon mixture, onion, cilantro, chipotle, sugar and garlic in food processor until smooth. Combine 1 tablespoon mixture with Hellmann's® or Best Foods® Real Mayonnaise and lime juice. Refrigerate until ready to use.
Combine remaining mixture with chicken in resealable plastic bag; turn to coat. Close bag and marinate 30 minutes.
Remove chicken from marinade, discarding marinade. Grill or broil chicken, turning once, until chicken is thoroughly cooked, about 8 minutes. Shred chicken and keep warm.
Evenly spread beans on tostadas, then top with chicken, mango and radish. Drizzle with mayonnaise mixture. Garnish, if desired, with cilantro leaves.