1. Bring 2 cups of water to a boil in a small saucepan. Add orzo and stir thoroughly. Cook for 10 minutes over medium-high heat, adding peas for the last 2 minutes. Drain and rinse with cold water. Drain thoroughly.
2. Combine orzo, peas, pine nuts, 1/2 cup basil, onion, red bell pepper, half of the garlic, and vinegar in a medium bowl. Season with salt and black pepper to taste.
3. In a blender, combine remaining basil and garlic, beans, and 1/2 cup water to make pesto fluff. Cover and blend until smooth; season with salt and pepper. Transfer to a piping bag or resealable plastic bag (snip off a small corner when ready to use).
4. Cut off the top and a thin slice off the bottom of tomatoes to create a flat base so they stand upright. Use a melon baller to scoop out and discard seeds. Fill tomatoes with orzo mixture and top with pesto fluff. Serve chilled or at room temperature.