Substitutions:

• In place of the Trader Joe's Umami seasoning, you can also use any umami seasoning or mushroom powder. Lillie's Q Umami Boost Seasoning is a great alternative. Whole Foods also carries an Organic Umami Seasoning that works as well. 
• If you don't have umami seasoning, substitute 1 tablespoon of tomato paste and one tablespoon of soy sauce, tamari, or coconut aminos. Stir it into the onions and garlic just before adding the tomatoes, and give it a minute or two to caramelize.
• Use any cooking greens you have on hand in place of the kale. If using spinach, fold it in right at the end and cook just until it's wilted in.
• I love chickpeas in this recipe, but I've also made it with cannellini beans and butter beans. Both are delicious.
• No feta? Use whatever cheese you have on hand. Parmesan, Mizithra, mozzarella, or you could even dot the top with plops of low-fat ricotta. 

Note:

• Good tomatoes are ESSENTIAL to the outcome of this dish. Buy the best tomatoes you can afford. If possible, use imported Italian tomatoes such as Mutti or Pomi. My favorite domestic brand is Muir Glen Organic.
• Second, don't use low-sodium chickpeas; they just aren't seasoned enough.
• Finally, taste and adjust the salt before adding the feta. The amount of salt this recipe needs depends heavily on the sodium in your canned tomatoes, which varies dramatically between brands.
• Several cranks of good ol' black pepper boost the flavor as well, and if you like some heat, you can always add a pinch of red pepper flakes.