Salt the vegetables: In a bowl, combine the sliced bell pepper, onion, carrots, and jalapeño. Toss with 1 tablespoon kosher salt and let sit at room temperature for 1 hour. Rinse and strain well.
Poach the heart: Bring 4 quarts of water mixed with ½ cup kosher salt to a slow simmer. Add the diced venison hearts and poach until just cooked through, 1–2 minutes. Drain and set aside.
Combine: In a clean glass jar, layer the poached heart, prepared vegetables, vinegar, lemon juice, olive oil, coriander, fennel, and rosemary.
Refrigerate: Cover the jar with a lid and refrigerate for 4 days before serving.
