Without butter, cheese, or cream, it’s not easy to make a pasta sauce.  One good technique is to use a mild, pale-colored vegetable puree.  For a recipe using 240ml (8 0z) of linguine with vegetables, boil, steam or microwave until very tender 1 cup (240ml) or more cauliflower florets or corn kernels. Purée until smooth with about 120ml (½ cup) water, broth, or almond milk, and 5ml (1 teaspoon) cornstarch (blenders make finer purées then processors, by far!).  Once you’ve sautéed the aromatics like garlic and shallots, add the prepped vegetables, then the cooked pasta; toss to blend.  Add the sauce.  Toss until the sauce thickens and coats.  You’ll need to adjust and heighten the flavor with salt, pepper, maybe hot sauce, lots of chopped bright herbs like a mix of basil, mint, and tarragon, grated lemon peel, or freshly grated ginger root.