Pat the chicken dry and season both sides with 1 teaspoon of salt and 1/2 teaspoon pepper. In a shallow bowl, add the cassava flour. Dredge each piece of chicken into the flour so that they are evenly coated, shaking off any excess.
In a large, deep skillet, heat the oil over medium-high heat. Place the chicken into the skillet and cook until golden brown on each side, 2 to 3 minutes per side. Transfer to a clean plate and set aside.
Reduce the heat to medium and add the cherry tomatoes, red pepper flakes, garlic, shallot, sun-dried tomatoes, 1/2 teaspoon salt and 1/2 teaspoon of pepper. Cook, tossing often, until the tomatoes begin to blister and soften, about 4 minutes.
Add the tomato paste and stir until well combined (it’s okay if the tomatoes begin to burst open and break). Stir in the chicken broth until the tomato paste is well incorporated and reduced by half, about 3 minutes.
Stir in the coconut milk and bring the sauce to a rapid simmer. Once simmering, reduce to a light and steady simmer (about medium to medium-low heat) and nestle the chicken back into the sauce and top with the basil. Cook, simmering uncovered, until the sauce has thickened and the chicken is cooked through, 7 to 10 minutes.
Remove from the heat and stir in the lemon juice. Top with toasted pine nuts (if using) and more fresh basil before serving.