Step 1

Heat a small saucepan over medium-high heat. Add oil and onion and cook, stirring often, for 4–5 minutes or until tender and golden. Add garlic, finely chopped mushroom and thyme and cook, stirring often, for a good 5–8 minutes or more, until the mushrooms have released their juices and these have evaporated, so that the mushrooms are almost dry, tender and golden (this is important because you don't want any excess moisture or your patties won't hold together). Add paprika and cook for a further 20–30 seconds.

Step 2

Transfer to a food processor, add tempeh and breadcrumbs and pulse until finely ground. Season with salt and pepper. Shape into 4 large patties, cover and chill for at least 30 minutes, or up to 2 days if preparing ahead of time. If you don't have a food processor, finely chop the tempeh, add onion mixture and breadcrumbs then, using your hands, scrunch everything together until it holds its shape.

Step 3

Heat a large saucepan over medium-high heat, add a splash of olive oil and cook the patties for 3–4 minutes on each side, or until golden. Grill buns on the cut side until golden. Spread a little mayonnaise and pesto onto the base of each burger bun, then add a patty, a few micro greens or lettuce, some onion slices. Top with smashed avocado and spread a little relish on the cut side of the top bun and place over.