Here's the Gurobi code to solve the optimization problem:

```python
import gurobipy as gp

# Create a new model
m = gp.Model("food_optimization")

# Create variables
knishes = m.addVar(lb=0, vtype=gp.GRB.CONTINUOUS, name="knishes")
chicken_drumsticks = m.addVar(lb=0, vtype=gp.GRB.INTEGER, name="chicken_drumsticks")
steaks = m.addVar(lb=0, vtype=gp.GRB.INTEGER, name="steaks")

# Set objective function
m.setObjective(9.54 * knishes + 1.56 * chicken_drumsticks + 4.96 * steaks, gp.GRB.MINIMIZE)

# Add constraints
m.addConstr(23 * knishes + 7 * steaks >= 20, "iron_constraint1")
m.addConstr(2 * chicken_drumsticks + 7 * steaks >= 37, "iron_constraint2")
m.addConstr(23 * knishes + 2 * chicken_drumsticks + 7 * steaks >= 34, "iron_constraint3")
m.addConstr(15 * knishes + 3 * chicken_drumsticks >= 20, "fiber_constraint1")
m.addConstr(15 * knishes + 3 * chicken_drumsticks + 23 * steaks >= 20, "fiber_constraint2")
m.addConstr(13 * knishes + 5 * chicken_drumsticks >= 26, "fat_constraint1")
m.addConstr(13 * knishes + 24 * steaks >= 67, "fat_constraint2")
m.addConstr(5 * chicken_drumsticks + 24 * steaks >= 36, "fat_constraint3")
m.addConstr(13 * knishes + 5 * chicken_drumsticks + 24 * steaks >= 36, "fat_constraint4")
m.addConstr(15 * knishes + 20 * chicken_drumsticks >= 25, "protein_constraint1")
m.addConstr(15 * knishes + 15 * steaks >= 34, "protein_constraint2")
m.addConstr(15 * knishes + 20 * chicken_drumsticks + 15 * steaks >= 34, "protein_constraint3")
m.addConstr(7 * knishes - 7 * steaks >= 0, "custom_constraint1")
m.addConstr(15 * knishes + 23 * steaks <= 102, "fiber_constraint3")
m.addConstr(15 * knishes + 3 * chicken_drumsticks + 23 * steaks <= 139, "fiber_constraint4")
m.addConstr(13 * knishes + 5 * chicken_drumsticks + 24 * steaks <= 194, "fat_constraint5")
m.addConstr(15 * knishes + 20 * chicken_drumsticks <= 143, "protein_constraint4")
m.addConstr(20 * chicken_drumsticks + 15 * steaks <= 88, "protein_constraint5")


# Resource Constraints
m.addConstr(23 * knishes + 2 * chicken_drumsticks + 7 * steaks <= 133, "iron_resource")
m.addConstr(15 * knishes + 3 * chicken_drumsticks + 23 * steaks <= 145, "fiber_resource")
m.addConstr(13 * knishes + 5 * chicken_drumsticks + 24 * steaks <= 240, "fat_resource")
m.addConstr(15 * knishes + 20 * chicken_drumsticks + 15 * steaks <= 168, "protein_resource")


# Optimize model
m.optimize()

# Print results
if m.status == gp.GRB.OPTIMAL:
    print('Obj: %g' % m.objVal)
    print('knishes:', knishes.x)
    print('chicken_drumsticks:', chicken_drumsticks.x)
    print('steaks:', steaks.x)
elif m.status == gp.GRB.INFEASIBLE:
    print("The model is infeasible.")
else:
    print("Optimization ended with status:", m.status)

```
