In a small saucepan, combine the lemon juice, lemon zest, garlic, agave syrup and dried basil. Heat on low heat until the agave has loosened and the ingredients are well combined. Remove from heat and set aside.
For the salad:
Preheat your oven to 375 F.
Combine the potatoes and asparagus with 2 tablespoons of oil in a large mixing bowl. Toss to coat, then spread on a large baking sheet. Coat the ears of corn with vegan butter and add them to the baking sheet.
Sprinkle all the vegetables on the baking sheet with garlic powder, onion powder, salt and pepper.
Bake 12 to 15 minutes, or until the asparagus reaches desired tenderness. Remove the asparagus to a large mixing bowl.
Before returning the baking sheet to the oven, turn the corn over and flip the potatoes to encourage even browning. Return to the oven and bake 7 minutes more. Remove the cobs of corn.
Spread the potatoes even over the entire baking sheet. Return to the oven for 10 minutes more or until they have reached desired tenderness when pierced by a fork.
Meanwhile, cut the corn kernels from the cobs and add to the large mixing bowl of asparagus. Also add the tomatoes and chopped red onion.
Once the potato wedges are finished baking, remove them from the oven and let cool until you are able to handle them. Add to the mixing bowl of vegetables. Toss all ingredients to mix.
Give a small stir to the dressing you set aside, then drizzle it over the salad. Gently toss to blend and coat the vegetables. Serve warm or the salad is also good after being refrigerated.