Break turkey into chunks and cook in a hot, lightly oiled pan. Season with salt and pepper. Brown well on one side (3 to 4 minutes) then toss until no pink remains, about 1 more minute. Remove from pan.
Add carrot to same pan and cook until starting to soften (1 to 2 minutes)
Add onion and cook until softened (1 to 2 minutes)
Remove carrots and onions from pan and combine with turkey.
Combine tomato, jalapeno, mint, and chili flakes in a bowl.
Combine lime juice, fish sauce, and ranch dressing.
Toss lettuce in dressing, top with turkey mixture and tomato mixture.