Set a large deep skillet or Dutch oven over medium heat. Add 2 tablespoons olive oil and let it warm for about 30 seconds.

Put the broken spaghetti into the skillet. Stir often for 3 to 4 minutes, until the pieces are golden brown in many spots and smell nutty.

Transfer the toasted spaghetti from the skillet to a plate and set it aside.

Add the chopped onion to the same skillet. Cook over medium heat for 4 minutes, stirring now and then, until the onion softens and starts to look glossy.

Add the sliced garlic, 1/2 teaspoon ground cumin, and a few grinds of black pepper to the skillet. Stir for 30 seconds, just until the garlic smells fragrant.

Pour the tomato sauce into the skillet. Stir it with the onion and garlic for 1 to 2 minutes, until it looks a little darker and slightly thicker.

Pour the vegetable broth into the skillet. Add 1/2 teaspoon kosher salt, raise the heat to medium-high, and bring the liquid to a gentle simmer.

Return the toasted spaghetti to the skillet. Press the pasta down with a spoon so the pieces are mostly covered by the liquid.

Cover the skillet, lower the heat to medium-low, and cook for 6 minutes.

Uncover the skillet and stir well, separating any pasta pieces that are sticking together. Add the drained pinto beans and fold them into the pasta.

Cover the skillet again and cook for 4 to 5 minutes more, until the pasta is tender and most of the liquid has cooked down into a loose sauce.

Turn off the heat. Squeeze 2 lime wedges over the skillet and stir once to mix the juice into the sauce.