- Bring large pot of lightly salted water to a boil for pasta.
- Make pesto: in dry small skillet, toast pine nuts over medium-low heat, stirring, until light golden and fragrant, 2 to 4 minutes.
- Transfer to small bowl and let cool.
- Using a mortar and pestle or side of chef's knife, mash garlic and 1 teaspoon salt until paste forms.
- Transfer to food processor along with toasted pine nuts, basil and pepper flakes and process until finely chopped.
- Add tofu and oil and process until mixture is smooth.
- Transfer to medium bowl and season with freshly ground pepper to taste.
- Set pesto aside.
- Place potatoes in a steamer basket in large saucepan over 2 cups boiling water and season with remaining ¼ teaspoon salt.
- Cover and cook 4 minutes.
- Add green beans to steamer basket, cover and cook until potatoes and beans are tender, 8 to 10 minutes.
- Transfer vegetables to large serving bowl; cover to keep warm.
- Measure ⅓ cup water remaining in steamer and stir into pesto until well blended.
- Meanwhile, add penne to boiling water; stir to prevent sticking.
- Cook until just tender, 8 to 10 minutes.
- Drain pasta, reserving a little cooking water.
- Add pasta to vegetables along with pesto, adding a little reserved pasta water if needed.
- Toss to coat well and serve hot.