Combine chopped onion, garlic cloves, and trimmed jalapeño peppers in a food processor; process until ground. Add chicken breast halves; process until finely ground. Heat a large skillet over medium-high heat. Add canola oil. Add chicken mixture; sprinkle with salt and pepper. Sauté 10 minutes, stirring to crumble. Heat tortillas according to package directions. Place 2 tortillas on each of 4 plates; divide chicken mixture evenly among tortillas. Combine sliced radish, chopped avocado, and fresh lime juice; divide mixture evenly among tacos. Garnish with cilantro leaves.