Place chicken in slow cooker. In a medium bowl, mix together tomatoes, chili powder, cumin, paprika, salt, pepper and coriander. Pour over chicken.
Top chicken with garlic, sliced peppers, and onion. Cover and cook on low for 6 hours. Remove chicken and slice into strips (or shred if desired). Return to slow cooker and mix with peppers and onions.
Fill tortillas with chicken and veggies. Serve with lime wedges for spritzing and grapes on the side.