Peel the yuca and cut into 1-inch cubes, then boil in a pot of salted water for 12 minutes until fork-tender but still firm.
Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Drain the boiled yuca well and pat dry with a paper towel to ensure maximum crispiness.
Place the chicken breast on one side of the baking sheet and season with half of the olive oil, sea salt, black pepper, and dried oregano.
Toss the yuca cubes with the remaining olive oil and a pinch of salt, then spread them in a single layer on the other side of the baking sheet.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the yuca is golden brown.
While roasting, whisk together the lemon juice and minced garlic in a medium bowl.
Add the fresh watercress to the bowl and toss gently to coat with the dressing.
Slice the roasted chicken into strips and serve immediately over the bed of watercress with the crispy yuca on the side.