Preheat the oven to 450F or 425F convection. Line two baking sheets with parchment paper. Divide tofu, broccoli, and potatoes between the two baking sheets. Drizzle about 2 tablespoons oil and sprinkle ½ teaspoon salt onto each baking sheet and toss to coat. Bake for 20-25 minutes, or until tofu is light golden and potatoes are cooked through.
Add cucumbers to a bowl along with the lime juice and remaining ¼ teaspoon salt and toss to coat. Set aside.
In a medium pot over medium-low heat, add the oil, curry powder, and pepper. Cook, stirring constantly, for about 30 seconds to toast the spices. Add the tomatoes, cashews, soy sauce, mustard, and salt. Break the tomatoes open (with your hands, a spoon, or scissors - be careful of splatter!) to release their juices and stir everything together. Increase the heat to medium-high to bring to a simmer, then reduce the heat to low to maintain that simmer for 5 minutes, stirring occasionally.
Transfer to a high-speed blender and blend on high until totally smooth, making sure to leave room for the steam to escape (keep the lid barely cracked open).
Serve the roasted veggies and tofu smothered in the sauce and topped with herbs and cucumber.