Heat the olive oil in a large pot or Dutch oven over medium heat.
Add the chopped onions and diced potato.
Cover and cook, stirring occasionally, until softened, about 5 minutes.
Pour in the vegetable broth and bring the mixture to a boil.
Stir in the frozen lima beans and corn.
Continue to cook until the vegetables are tender, about 15 minutes.
Decrease the heat to low and stir in the soy milk.
Season generously to taste with salt and freshly ground black pepper.
For a creamy texture, use an immersion blender to partially puree the soup directly in the pot, leaving some chunks for texture. Alternatively, carefully transfer about 2 cups (480 ml) of the soup to a standard blender, puree until smooth, and stir it back into the pot.
Reheat gently if necessary, but do not boil. Ladle the chowder into bowls and garnish with chopped pimientos before serving.
Add a pinch of smoked paprika or a teaspoon of nutritional yeast when you season the soup to add a smoky or savory, cheesy depth of flavor.