Bring 1 cup of the water to a boil in a small saucepan. Add the bulgur and simmer, covered, for 15 minutes, or until the water is absorbed. Or if you can do this step ahead of time, simply add the bulgur to the boiling water, cover, and remove from the heat. Let stand for 30 minutes.

Heat the oil in a soup pot. Add the onion and sauté over medium heat until translucent. Add the garlic and bell pepper and continue to sauté, stirring frequently, until all are golden.

Add the remaining ingredients, except the garnishes, plus the cooked bulgur and the remaining 3 cups water. Bring to a rapid simmer, then lower the heat. Cover and simmer gently for 10 to 15 minutes, then remove from the heat.

Assemble each serving as follows. Fill each bowl about 2/3 full with soup. Top with some grated cheese, shredded lettuce, and diced tomatoes. Line the perimeter of each bowl with several tortilla chips, points facing upward, for a kind of star-shaped effect. The tortilla chips can be used to scoop up the solid parts of the soup or just nibbled along with the soup. Pass around a bowl of extra tortilla chips.