2 tablespoons minced fresh flat-leaf parsley
Salt to taste
For the tortilla strips
2 tablespoons olive oil
Three 6-inch corn tortillas, halved and cut into ¼-inch strips
To make the salsa, whisk together the oil, lime juice, jalapeño pepper, garlic, and sugar in a small bowl. Gently stir in the avocado, corn, red onion, and cilantro. Season to taste; set aside.
To make the soup, heat the oil in a Dutch oven over medium heat. Add the onion, bell pepper, celery and leaves, and garlic; cook, stirring occasionally, until the vegetables are crisp-tender, about 8 minutes. Add the cumin; stir for about 30 seconds.
Stir in the chicken stock or vegetable stock, tomatoes, beans, pepper, and red pepper flakes. Increase the heat to high and bring to a boil. Reduce the heat; cover and simmer until the vegetables are tender, about 20 minutes. Stir in the parsley and salt. Taste and adjust the seasoning.
While the soup is cooking, prepare the tortilla strips. Heat the olive oil in a large skillet over medium heat. Add the tortilla strips in a single layer. Cook, turning occasionally with tongs, until the strips are lightly browned and crispy, about 10 minutes. Transfer the strips to a plate lined with a paper towel.
Top each bowl of soup with tortilla strips and a mound of the salsa.
This soup will keep for up to 5 days in a covered container in the refrigerator. Prepare the salsa and tortilla strips the day of serving. Refrigerate the salsa in a covered container; store the strips in a tightly covered tin at room temperature.