Lay out brioche slices. Add 2 tablespoons jam to the center of 2, then top with remaining slices. Press edges lightly to create a seal.

Fill a deep, wide skillet with 2-inches oil and set over medium-high/high heat until oil reaches 340 degrees F. (Or use a countertop electric skillet.)

While oil heats, whisk to combine eggs, flour, milk, and sea salt. Spread turbinado or caster sugar out in a shallow dish and set aside.

Working quickly, dip sandwich in batter, carefully lift out, letting some of the batter drain off, lower into the hot oil, and fry each side until light golden – 30 seconds to 1 minute per side. Use a slotted fish spatula to lift donut out of oil, letting any excess oil drip off, then set in sugar filled dish and turn to coat. Repeat for second sandwich.

Slice sandwiches in half, and enjoy immediately (watch out for the hot jam!).