Nitrite remains a central component in industrial cured meat processing for its role in providing colour stability, oxidative protection, and microbial safety. However, synthetic nitrite is associated with the formation of nitrosamines, leading to increased health concerns and negative consumer perception of synthetic additives, thereby increasing demand for healthier meat products produced with natural nitrite sources. This study employed a two-stage design to assess microbial nitrate curing in cooked sausages and its extension to vegetable powders. In Stage 1, sodium nitrate (100 mg/kg) combined with Staphylococcus carnosus was incubated at 30 or 40 °C for 90 or 180 min. Incubation at 30 °C yielded residual nitrite concentrations of 18–29 mg/kg, corresponding to 35–40% of those in nitrite controls, and resulted in equivalent colour (CIE ΔE* < 2) and oxidative stability (0.07–0.09 mg MDA/kg versus 0.08 mg MDA/kg in the control). In Stage 2, application of red beet (2%) and leek (1%) powders supplying 100 mg/kg NO_3⁻ produced adequate curing but induced substantial compositional and sensory deviations, including higher redness (CIE a* ≈ 23 versus 15), fourfold higher lipid oxidation (0.35–0.42 mg MDA/kg), and intensified vegetable aroma and sweetness. These findings demonstrate that microbial nitrate reduction at 30 °C effectively reproduces the technological performance of direct nitrite addition, whereas vegetable-based nitrate curing introduces significant colour, oxidative, and sensory differentiation, highlighting both potential and limitations of microbial nitrate curing.