01 - Preheat oven to 425°F. Line a baking sheet with parchment paper.
02 - Arrange green beans and red onion slices on the prepared baking sheet. Drizzle with 2 tablespoons olive oil, season lightly with salt, and toss to coat evenly. Roast for 18–20 minutes, stirring halfway through, until the beans are golden and tender-crisp.
03 - While vegetables roast, rinse millet under cold running water and drain well. Combine millet, 2 cups water, and 1/2 teaspoon salt in a medium saucepan. Bring to a rolling boil over medium-high heat, then reduce to low, cover, and simmer for 15 minutes until all liquid is absorbed. Remove from heat and let stand covered for 5 minutes. Fluff grains gently with a fork.
04 - In a small bowl, whisk together extra-virgin olive oil, lemon juice, Dijon mustard, honey, minced garlic, salt, and pepper until the dressing is smooth and emulsified.
05 - Transfer the warm, fluffed millet to a large serving bowl. Add the roasted green beans and onions, halved cherry tomatoes, and chopped parsley. Drizzle the dressing over the top and toss gently until all ingredients are evenly coated.
06 - Serve the salad warm. Scatter toasted pumpkin seeds or sliced almonds and crumbled feta cheese over each portion, if desired.