Bring a large pot of salted water to boil. Add the sliced carrots and cook for 8-10 minutes until they're tender but still have a slight bite. They should be easily pierced with a fork but not mushy. Immediately drain and rinse with cold water to stop the cooking process.

In a large mixing bowl, whisk together the lime juice, lemon juice, orange juice, olive oil, salt, and black pepper until well combined. The mixture should be bright and tangy.

Add the cooled carrots, sliced red onion, and minced jalapeños to the citrus marinade. Toss everything together until the carrots are well coated. Cover and refrigerate for at least 2 hours, or preferably overnight, stirring occasionally.

Just before serving, gently fold in the chopped cilantro, diced avocado, and fresh mint. Taste and adjust seasoning with additional salt, pepper, or lime juice as needed.

Serve the carrot ceviche chilled in small bowls or on individual plates. Garnish with extra cilantro leaves and serve with tortilla chips, tostadas, or crusty bread if desired.