Place the lentils, 3 cups (720 ml) water, and 1/2 teaspoon salt in a medium saucepan. Bring to a boil, then reduce to a steady simmer. Cook until the lentils are tender but still holding their shape, about 20 to 25 minutes. Drain any excess water and set aside.

Meanwhile, place the rice, 2 cups (480 ml) water, and 1/4 teaspoon salt in another saucepan. Bring to a boil, cover, reduce the heat to low, and cook until the water is absorbed and the rice is tender, about 15 to 18 minutes. Remove from the heat and let stand, covered, for 5 minutes before fluffing.

Bring a pot of generously salted water to a boil. Cook the pasta according to the package directions until tender. Drain well and set aside.

While the pasta cooks, heat the oil in a large skillet over medium-high heat. Add the sliced onions and cook, stirring often, until deep golden brown and crisp at the edges, about 12 to 16 minutes. Watch closely near the end because onions can darken quickly. Transfer the onions to a paper towel-lined plate. Reserve 1 tablespoon of the oil in the skillet and carefully discard or save the remaining oil for another use.

Reduce the skillet heat to medium. Add the garlic, cumin, cayenne, remaining 1/4 teaspoon salt, and black pepper to the reserved oil. Stir for about 30 seconds, just until fragrant. Add the crushed tomatoes and vinegar. Simmer, stirring occasionally, until slightly thickened, about 10 minutes. Stir in up to 1/4 cup (60 ml) water if the sauce becomes too thick.

Warm the chickpeas in the tomato sauce for 2 to 3 minutes. Taste the sauce and add more cayenne if your family likes heat.

To serve, layer rice, lentils, and pasta in individual bowls or on a large platter. Spoon the chickpea tomato sauce over the top and finish with the crispy onions. Let everyone mix the layers together as they eat.