Bring a large pot of salted water to a rolling boil over high heat. Add orzo and cook according to package instructions until al dente, usually 8-10 minutes. Drain and let cool in a large bowl.

Preheat a grill pan over medium-high heat. Husk corn and grill for 10-12 minutes, turning occasionally, until charred. Remove from heat, let cool slightly, then cut kernels off the cob.

On the grill pan, add white parts of scallions and grill for 1-2 minutes until softened. In a skillet, heat oil and sauté minced garlic until fragrant, about 1 minute. Allow to cool, then slice scallions.

In a blender, combine sautéed garlic, grilled scallions, lemon zest, lemon juice, vinegar, oils, miso paste, and salt. Blend until smooth. Add fresh dill and pulse until incorporated.

In the bowl with cooled orzo, add grilled corn, scallions, artichoke hearts, edamame, oregano, and arugula. Drizzle dressing and toss gently until coated. Adjust seasoning with salt and pepper.

Serve immediately or chill for an hour to enhance flavors. Top with vegan parmesan if desired.