Cut the breasts lengthwise to obtain thinner pieces.
In a bowl, mix all the marinade ingredients. Add the chicken and coat well.
Let marinate in the refrigerator at least 1 hour.
Preheat the oven to 200°C (400°F).
Place the breasts on a baking sheet lined with parchment paper.
Pour a little marinade over the chicken.
Cook for 18 to 22 minutes, until fully cooked.
Put under the broiler for 2 to 3 minutes to obtain a nice color.
For the chimichurri sauce, in a food processor, chop the parsley, cilantro, mint and garlic. Add the salt, pepper and chili flakes. Incorporate the oil, vinegar and water. Mix until you obtain a slightly thick sauce.
Serve the chicken hot with the chimichurri sauce.