You need

• 8 oz halloumi made with microbial rennet, cut into 4 slabs 1/2 inch thick
• 1/2 red onion, sliced paper-thin
• 1/2 cup red wine vinegar
• 1 tsp sugar
• 1/2 tsp salt
• 1/3 cup chili jam or sweet chili relish, fish-sauce and shrimp-paste free (read the label, most Thai-style brands are not)
• 1/4 cup mayonnaise
• 1 tsp lemon zest
• 1/4 cup cornstarch
• Neutral oil for shallow frying, about 1 cup
• 4 slider buns
• 2 tbsp butter, softened
• 1 cup shredded iceberg lettuce

Method

1. Soak the halloumi slabs in cold water for 20 minutes, then dry them hard between towels. Wet halloumi steams instead of browning.
2. Pack the red onion into a jar with the vinegar, sugar and salt. Leave it 20 minutes, shaking once. It will go pink and lose its bite.
3. Stir the mayonnaise with the lemon zest. Butter the cut sides of the buns and toast them face down in a dry skillet over medium for 90 seconds, until the edges go brown.
4. Dredge the dried halloumi in cornstarch and press off the excess. Heat 1/4 inch of neutral oil to 350F.
5. Fry the slabs 2 minutes per side until blistered and deep gold. Move straight to a rack, not paper, so the crust holds.
6. Build bottom up: lemon mayo, iceberg, halloumi, a heavy spoon of chili jam, drained pickled onion. Lid on, eat immediately. Halloumi turns to rubber as it cools.

From behind the bar: Soak the halloumi in cold water 20 minutes to pull the brine, then dry it aggressively. Salt out, moisture out, crust in.