Heat a nonstick skillet over medium heat and add 1 tablespoon olive oil. When shimmering, add the minced garlic and stir for 15 seconds until fragrant.

Add the sliced onions and bell pepper. Sauté 2–3 minutes until they begin to soften.

Add the mushrooms and zucchini. Cook 3–4 minutes, stirring occasionally, until vegetables are tender and most moisture has evaporated.

Add the spinach and roasted tomato; cook 30–60 seconds until spinach wilts. Stir in smoked paprika, dried oregano, 1/4 tsp salt, 1/8 tsp black pepper and 1/2 tsp lemon juice. Taste and adjust seasoning as needed. Remove from heat and keep warm.

Cheese & Toppings

Toast the buttered bun halves in a separate clean skillet over medium heat (or under a broiler) until golden, about 60–90 seconds per side. Remove and set aside.

Spread 1 tablespoon mayonnaise on the bottom bun half and 1/2 teaspoon Dijon mustard on the top bun half (or reverse to taste).

Place 1 slice of cheese on the bottom bun. Pile the warm vegetable Reggie filling on top of the cheese so residual heat slightly melts it. Add leaf lettuce or arugula on top of the vegetables and scatter pickled jalapeños if using.

Egg*

In a small nonstick skillet, heat 1/2 tsp butter or oil over medium-low. Crack the large egg into the skillet. For sunny-side-up: cook gently until whites are set but yolk remains runny, about 2–3 minutes; cover with a lid for 30–45 seconds if whites need finishing. For over-easy: cook 1–2 minutes then gently flip and cook 10–20 seconds. Season the egg with 1/16 tsp salt and a pinch (1/32 tsp) black pepper.

Using a spatula, transfer the cooked egg onto the layered vegetables on the bottom bun (on top of the lettuce or cheese depending on assembly preference).

Assemble & Serve

Top the assembled bottom bun (cheese + veggies + egg) with the top bun. Press gently to secure.

Cut the sandwich in half if desired and serve immediately while the egg is warm and yolk is runny. Provide a napkin — the runny yolk will make the sandwich rich and saucy.