Grilled Portobello Burger with Onion Jam

This is a vegetarian burger with real backbone. Meaty portobello caps get brushed with garlic-balsamic oil and charred on a hot grill pan until tender but still holding their shape. The umami from the mushrooms does the heavy work of replacing beef, and the grill char gives it that irreplaceable smoky edge.

The red onion jam is worth the 25 minutes it takes to cook down. Thinly sliced red onions wilt in olive oil with thyme, then simmer in red wine until absorbed, followed by honey and red wine vinegar that reduce into a glossy, jammy sweet-and-sour compote.

The horseradish yogurt cream is the final layer. Drained yogurt thickens like sour cream, then whisked with prepared horseradish gives you a sharp, creamy sauce that cuts through the onion sweetness and mushroom richness.

Pro Tips

• Drain the yogurt at least 60 minutes for proper thickness. Wet yogurt sauce slides off the burger.
• Cover the pan while cooking onions so they wilt evenly without browning too fast.
• Don’t stack raw portobellos in the marinade too long. Ten minutes is enough; they absorb oil fast and can turn greasy.
• Toast the buns well so they stand up to the juicy mushroom and wet jam without going soggy.

Variations

• Swap red wine for port, balsamic vinegar, or a dark beer in the onion jam.
• Add a slice of goat cheese, smoked mozzarella, or sharp cheddar under the mushroom.
• Use grilled eggplant slices or thick zucchini planks in place of portobellos.