The night before: Stir together the beef stock, soy sauce, balsamic vinegar, tomato paste, thyme, black pepper, and garlic. Put the beef in a gallon-size Ziplock bag.
Pour the marinade into the bag with the beef. Seal the bag, pressing out as much air as you can.
Allow the beef to marinate in the refrigerator overnight. Flip it a few times, allowing the marinade to penetrate the beef from all sides.
The following evening: Remove the beef from the marinade and pat it dry. Set your Instant Pot to “high sauté” and add butter and avocado oil. Once the butter melts, add the thinly sliced red onions and let them soften.
Push the onions to one side of the pot and add the beef. Allow the beef to brown for a couple of minutes on all sides.
Next, turn the pot off and pour the marinade from the bag into the pot. The liquid level should reach the minimum required for pressure cooking by the Instant Pot. Put the lid on the pot and close the vent.
Set the pot to high pressure on the bean/chili setting and set it to pressure cook for 5 minutes.
At the end of the cook time, quick release the pressure and use tongs to lift the London broil out of the liquid.
Check the temperature of the thickest part of the beef. It should have reached a safe minimum internal temperature of 145°F (63°C). Let the beef rest for 10 minutes on a plate.
To make the gravy, set the Instant Pot to “high sauté.” Let the marinade and onion mixture bubble for 5 minutes, and then whisk in the xanthan gum. Let the gravy thicken over the heat for about 5 minutes, whisking occasionally.
To serve: Thinly slice the beef against the grain and ladle on the gravy.
To make the optional sides:
Preheat the oven to 400°F (200°C)F.
Rinse and trim the Brussels sprouts. Cut them in ½ or into ¼s, depending on their size. Spread them in a single layer on a dark baking sheet.
Drizzle the sprouts with olive oil and sprinkle with Everything but the Bagel Seasoning. Roast in the top third of the preheated oven for 20-30 minutes, flipping halfway through cooking time.
For the mashed potatoes, peel and chop your potatoes. Cover with water in a large pot, and let them boil for about 20 minutes. Drain them well.
Add butter, milk, salt, and pepper to the hot potatoes. Mash until smooth (I like to use a hand masher).
Serve the London broil and gravy on top of the mashed potatoes, with the Brussels sprouts on the side.
This is a level 2 recipe (transition or weight maintenance). A (realistically sized) serving of the London broil by itself is under 500 calories. However, with the pile of mashed potatoes and roasted Brussels sprouts, my meal was over 900 calories!If you aren’t looking for a meal that is quite so hearty, you can easily switch the sides to make a moderate calorie meal. Swap the mashed potatoes for mashed cauliflower and go lighter on the butter. Use less oil on the Brussels sprouts, or serve salad greens with a light dressing instead.The key to a lighter meal here is that you want to add in non-starchy veggies without lots of oil. Non-starchy veggies give a big boost to the volume of meals for very few calories. Added oils and fats, on the other hand, are very high calorie, typically 100-120 calories per tablespoon.Remember that regardless of the dietary lifestyle you’ve chosen (low carb, keto, etc.) you need to maintain a calorie deficit to lose weight. If you’re not meeting your weight management goals with your current plan, it might be a good idea to keep track of added fats. It can be really easy to overdo it with these healthy foods, including olive oil. (Trust me- I've been there!)Nutrition information is for one serving of the London broil and gravy with no side dishes.