Press the tofu for 15 minutes. To do this, use a tofu press or place the tofu between two flat surfaces with something heavy on the top.
Cut the tofu into bite-sized cubes and place it into a bowl. Add 1 tablespoon of lime juice, 1 tablespoon of soy sauce, and 1 teaspoon of maple syrup. Toss to cover all sides of the cubes.
Cut the ends from the lemongrass stalks and peel the tough outer skin. Cut the stalks lengthwise, then dice them into small pieces.
Add the lemongrass, garlic, ginger, red chili, soy sauce, lime juice, and maple syrup to a spice grinder or small food processor. Blend until you have a smooth paste.
In a small cup or bowl, combine 1 tablespoon of cornstarch with 1 cup of water.
Add the lemongrass paste to a small saucepan over medium heat. Slowly add the cornstarch and water, whisking it with the paste. Simmer the sauce until it starts to bubble and continue simmering on low, stirring occasionally.
While the sauce simmers, cook the tofu, steam the veggies, and prepare the rice noodles.