First, set a large pot of salted water to boil. Once the water starts boiling, add the pasta and cook until al dente according to package directions. Reserve ½ cup of the pasta water. Drain the pasta into a large mixing bowl.
While the water is coming to a boil, make your avocado pesto. To make the pesto, add the basil, avocado, garlic, lemon juice, parmesan cheese and sunflower kernels to your food processor or blender. Pulse a few times and then start adding the olive oil. Blend until smooth. Season with salt and pepper, to taste. Set aside.
While the pasta is cooking, cook the tomatoes. In a large skillet, heat the olive oil over medium heat. Add the thyme sprigs and garlic. Once the garlic sizzles, add the tomatoes and season lightly with salt and pepper. Once the tomatoes start popping (about 5 minutes), add the balsamic and cook on medium high heat for about five minutes or until the balsamic is reduced and caramelized. Turn the heat off and discard the thyme sprigs.
Add the avocado pesto to the bowl that has the drained pasta. Stir, adding the reserved pasta water as necessary. Stir gently until the pasta is well coated in pesto. Top with balsamic cherry. Garnish with crushed red pepper flakes, basil, thyme and parmesan cheese, if using. Serve immediately.