2 small yellow crookneck squash or yellow or green zucchini (about 7 ounces)
Salt and freshly ground pepper
4 large cloves garlic, minced (about 2 tablespoons)
1/4 teaspoon turmeric, or to taste
1 1/2 to 2 cups whole milk yogurt, labneh (Middle Eastern strained yogurt, often labeled kefir cheese) or a mixture of both
Cayenne pepper to taste
3 tablespoons coarsely chopped walnuts, lightly toasted (optional, for garnish)
1. Heat the broiler.
2. Set the pepper on a slotted broiler pan or in a roasting pan, lined with foil if you like. Broil, turning pepper a few times, until it is charred on all surfaces, about 7 to 12 minutes. Remove from the broiler.
3. If you have broiled the pepper on foil, enclose it in the foil; otherwise put the pepper in a bowl and cover; or put it in a plastic or paper bag and close bag. Set aside until cool enough to handle, then peel with aid of a paring knife. Cut it in half, draining off any liquid. Discard the caps and remove the seeds.
4. Rinse the spinach. Put the spinach in a large sauté pan (10-inch) with the water clinging to its leaves. Cover and cook over medium-high heat, stirring occasionally, until wilted, about 3 to 5 minutes. Drain it in a colander and rinse it briefly with cold water. Squeeze the spinach by handfuls to remove excess water. Chop the spinach; you should have about 1 1/8 cups.
5. Dry the pan used to cook the spinach. Heat 3 tablespoons of oil in the pan over medium heat. Add the onion and cook, stirring occasionally, until it is soft but not brown, about 5 minutes.
6. Cut the squash in a very small dice, about one-fourth inch by one-fourth inch by one-half inch; you should have about 1 2/3 cups.
7. Add the squash to the pan, sprinkle with salt and pepper and cook, stirring occasionally, for 3 minutes. Cover and cook until the squash is tender, about 2 more minutes. Add the garlic and turmeric and sauté, stirring often, for 1 minute. Stir in the spinach, sprinkle with salt and pepper and cook, stirring often, for 2 minutes to evaporate its excess moisture. Transfer the mixture to a bowl and cool to room temperature.
8. Cut about one-third of the roasted red pepper in thin strips and reserve for garnish. Dice the remaining pepper. Mix the dice into the spinach mixture.
9. Stir the yogurt until smooth. Stir it lightly into the vegetable mixture. Taste and adjust seasoning, adding cayenne pepper to taste. Refrigerate for about 2 hours to marry the flavors. This makes a scant quart of dip.
10. Serve cold, garnished with reserved pepper strips, drizzled with olive oil if desired and sprinkled with walnuts.