fixings of your choice: (sprouts, onion, tomato avocado, blue cheese, etc)
for the sauce:
1 teaspoon olive oil
¼ onion, grated
1 clove of garlic, minced
¾ cup ketchup
2 tablespoons dijon mustard
2 tablespoons apple cider vinegar
2 tablespoons maple syrup
1 tablespoon worcestershire (I use the vegan brand)
½ to 1 teaspoon sriracha or hot sauce
salt and pepper, to taste
Make the sauce. In a small saucepan, heat oil. Add onion and garlic. Stir until translucent. Stir in the rest of the ingredients. If the mixure is not already bubbling, increase heat. As soon as it bubbles, reduce to a simmer. Let it reduce and thicken (5-10 minutes), stirring occasionally. Taste and adjust seasonings to your liking - sweetness, spice level, salt, etc.
Depending on the size of your portobello's, either trim to fit the size of your slider bun, or cut into strips. (To make slider-sized burgers and not waste mushroom scraps, I made some of both - cut squares like the one pictured, and made others with mushroom strips).
Liberally brush both sides of the mushrooms with the sauce and let them marinade for at least 15 minutes, up to 30.
Heat broiler or grill, cook mushrooms, flipping halfway through. (the time will completely depend on the heat of your broiler or grill). Grill should be a few minutes per side, I broiled mine in the oven for about 3-5 minutes per side. I have a really hot broiler.
When mushrooms are done cooking, brush with more sauce and serve with whatever fixings you like.
Recipe by Love and Lemons at https://www.loveandlemons.com/bbq-portobello-mushroom-sliders/