Preheat oven to 350°F (≈175°C). Slice ~⅓ off top of each mini pepper; remove seeds. Reserve chopped peeled bits (¾ cup) for filling.
In skillet over medium heat, cook ground beef + reserved pepper bits until browned; drain fat.
Stir in taco seasoning mix and water; simmer until thickened. Let mixture cool slightly.
Place each pepper upright in baking sheet; spoon beef mixture into each pepper fully.
Bake for 8–10 minutes.
Meanwhile, make cilantro cream sauce: blend sour cream, cilantro, garlic, and lime juice until smooth; chill.
Remove peppers, top with shredded cheddar, return to oven 1‑2 minutes until cheese melts.
Top with dollop of cilantro cream sauce before serving.