Cut potatoes into 1/4–1/2-inch fries (leave skin on if desired). Rinse in cold water until water runs clear to remove starch. Dry thoroughly on towels.

Toss dried potato sticks with 1 tsp cornstarch (optional), 2 tbs oil, paprika, 1 tsp salt and 1/2 tsp pepper until evenly coated.

Spread in a single layer on a parchment-lined or lightly oiled baking sheet. Roast 20–30 minutes, turning once, until golden and crisp. For extra crispness, finish under broiler 1–2 minutes, watching carefully.

Aioli

In a small bowl combine 1/2 cup mayonnaise, 1 tbs lemon juice, 1 tsp Dijon, 1 tsp minced garlic, 1/2 tsp honey or maple (optional), 1/4 tsp salt and 1/4 tsp black pepper. Whisk until smooth. Taste and adjust acidity or seasoning. Refrigerate until ready to use.

Burger Patties & Toppings

Heat a large skillet over medium-high heat and add 2 tbs olive oil. When shimmering, add the diced onion and sauté 3–4 minutes until translucent.

Add the minced garlic and chopped cremini and button mushrooms. Cook, stirring, until mushrooms release moisture and it evaporates and the mixture is lightly browned, about 8–10 minutes. Season with 1 tbs soy sauce, 1/2 tsp black pepper, 3/4 tsp salt, smoked paprika and chopped thyme. Remove from heat and let cool 8–10 minutes.

Transfer cooled mushroom mixture to a bowl. Add 3/4 cup panko breadcrumbs and 1 large beaten egg (or 1 flax egg: 1 tbs ground flax + 3 tbs water soaked 5 minutes). Mix until combined. If mixture feels too wet, add up to 2 tbs more panko. Form into 4 even patties (about 3/4-inch thick). Chill patties 15 minutes to help them hold shape.

If using a kiawe or charcoal grill, prepare medium-high heat. For indoor cooking, heat a grill pan or skillet over medium-high and brush lightly with oil. Brush patties lightly with oil. Grill patties 4–5 minutes per side until deeply browned and cooked through; handle gently when flipping. If using charcoal/kiawe, place patties over direct heat and cook similarly to impart smoky flavor.

During the last minute of cooking, toast buns cut-side down on the grill or pan with 1 tbs butter or oil until golden.

Assemble burgers: spread a generous tablespoon of aioli on the bottom bun, place lettuce leaf, grilled mushroom patty, 2–3 slices avocado, 1 tomato slice, a handful of sprouts, and top bun spread with additional aioli if desired.

Finishing & Serve

Plate burgers with fries. Optionally finish fries with an extra pinch of salt and a squeeze of lemon or sprinkle of chopped parsley.

Serve immediately while patties are warm and fries are crisp.