Make the sun-dried tomato pesto by pulsing the sun-dried tomatoes, garlic, pepper flakes, olive oil, thyme, and salt in a food processor until it comes together into a textured crumble. Add the walnuts, and pulse a few more timesSet aside.
Combine 1/2 cup of the hot water in a large mixing bowl along with two-thirds of the sun-dried tomato pesto. Add more hot water if needed to thin the pesto out - it should make a nice chunky sauce. Taste and add more of the pesto if you like - it's really a matter of personal preference at this point.
Top with the cherry tomatoes.
*To oven-roast cherry tomatoes: Heat oven to 350F degrees. Cut each tomato in half and arrange in a large oven-proof baking dish. Mix together a big splash of olive oil, a spoonful of brown sugar, and a few pinches of salt. Pour this over the tomatoes. Gently toss them a bit, making sure they all get coated. Arrange tomatoes cut-side up. Place in the oven and bake for 45 mintutes or so, until the tomatoes are shrunken and sweet.