Add the broccoli florets and 3 tablespoons water to a large sauté pan and cover; cook over medium heat for 3 to 4 minutes until the broccoli is softened but still bright green.
Remove the broccoli from the pan and pour off any remaining water.
While the broccoli cooks, place the chopped plum tomatoes and the milk in a blender and blend until smooth to make the sauce.
Return the sauté pan to medium heat, add the minced garlic and the sun-dried tomatoes (and a splash of the oil from the jar if using), and cook for about 30 seconds until fragrant.
Pour the blended tomato-milk sauce into the pan, season with the salt and black pepper, then add the broccoli back in and stir to coat.
Cook for about 2 minutes more, until the sauce is warmed through and slightly bubbly, then remove from heat and serve.