Halibut with Tomato and Spinach - Lidia

Ingredients

• 2 pounds fresh plum tomatoes, halved and cored (about 4 cups)
• 2 pounds skinless halibut fillet, cut into 2-inch chunks
• 1 ½ teaspoon kosher salt
• All-purpose flour, for dredging
• ¼ plus 2 tablespoons extra-virgin olive oil
• 6 garlic cloves, sliced
• ¼ teaspoon peperoncino
• 6 ounces fresh spinach, trimmed (about 12 packed cups leaves)